eBay item not received case gets auto closed 21 days later without resolution

OK. So this might be down to me being a bit of a newb and not getting how these things work.

TLDR disputed item took 21days and ebay auto closed 'due to no activity' even though conversation through ebay messaging were ongoing.. now I'm stuck without my item??

Essentially I wanted to get my old iPhone 5 working again. I bought through one order on ebay form one seller - but two separately listed items a battery and a screen.

Neither arrived. i had them shipped to my place of work a small business in small complex, though I don't use that address I don't usually have issues with mail, parcels are usually hand to the front counter - just the odd letter in the wrong box and thats sorted out easily enough.

So after a couple of weeks I had not had the items. I raised a dispute for each in ebay, and wrote most of the info in the battery entry - but to be sure I opened the screen entry also. They replied to the 'main' one and asked me to check again, check at the local post office. i had already been checking the letter box and asked the neighbouring business - nope, took me a day or two to get the time to trundle off to the post office - but no they don't have it/them either. they seller then advised once I confirmed the address they would resend. So I replied again with the address and waiting .. about a week later the battery showed up, I closed the case on that item, I gave it another day for the screen then on the screen case advised I had not received that and looking at the conversation I never saw they actually said they were sending the screen can they confirm. They then seemed to turn 'stupid' and started the process again .. I'll post the thread below… but basically I think they knew the system more then me and deliberately timed it out (I didn't know a time out would occur while we were still messaging)

Oct. 29 You didn't get the item
You requestedThe item
These items have not arrived. I think I have allowed plenty of time for the slow postage to WA (see other item).

Nov. 19You sent a message
Hi I received the resent battery today, but I have no received the screen - was the screen sent? I'm thinking that perhaps you missed this as it was a separate order?

Nov. 19The seller sent a message
Hi X, Thanks for getting in touch. I’m happy to tell you that your order shipped on 16/10/2018 and is expected to arrive at your address below between 16/10/2018 and 23/10/2018 : AdressRemoved. Please allow for a few days after this date for the package to arrive, as there sometimes can be delays in the delivery process. If you haven’t received your product within 10 working days, please let me know and I will offer you a choice of resolutions. I understand it can be frustrating to wait longer than you expected for your order, but I hope that your package arrives within this timeframe. Kind regards

Nov. 19 You sent a message
Hi, Last month I ordered a screen and battery to revive my iphone 5. I did so from one store as I thought it would meant they would ship together and arrive quicker then from overseas. The items did not arrive. As they are listed separately in ebay I raised the issue on both the battery and the screen items separately. You only replied on the battery and advised it would be resent (after I had to go and confirm with the post office that it was not held there) I had thought this would be both items. Only the battery then arrived and I collected it yesterday. But I still don't have a screen. So I continued the issue on this ebay item - but you replied I should wait longer on an item sent with an expected delivery over a month ago???

Nov. 19The seller sent a message
Are you sure your address is correct if no items have arrived then?

Nov. 19You sent a message
Yes. I am sure the address is correct. The initial two items did not arrive. I checked the mailbox, the surrounding businesses and the post office. I confirmed the address and you resent the battery and it arrived. I'm asking you to send the replacement screen.

Nov. 20The seller sent a message
Okay sure, which screen would you like us to send. Hopefully this will arrive this time.

Nov. 21You sent a message
It was for the original iphone 5.

Nov. 26The seller sent a message
Please close this case, and direct message us for a replacement

Nov. 26You sent a message
Hi Z, I don't think that is how cases are meant to be handled. I'm not sure why you'd like me to close the case ( a quick google shows many discussions where they adv not to do so). By closing the case I give up the ability for eBay to intervene. I closed the case on the battery as I received that item, but the screen has not shown up as yet.

Nov. 27The seller sent a message
Hey X Thank you so much for getting into contact with our team at Z. If you do not want to close the case, then you can return the item for a full refund. We just thought you wanted a replacement.

EBAY
We closed this request since there's been no activity for 21 business days.

So I can still direct message the seller - but I'm kind of over dealing with them I had thought they would have sent the screen after the 21st so I was surprised they asked to 'resolve' the case a week later.
I can't reopen a not sent item case a second time. Ebay don't seem to have a way to contact them - they say I need to open a case and then escalate it.. I could open another case under another topic .. but they might reject it as being false … I could use "item is not as described" and reference the other conversation?

Does anyone have any tips for me on how to proceed?