Opal Card Potential Pricing Errors during Maintenance

This discussion is primarily to make other Opal (transport card in Sydney) customers aware of potential pricing errors while taking replacement buses due to either scheduled maintenance or breakdowns.
Recently, I was traveling from station A -> station D. As there was some maintenance work going on between some stations en-route, we had to break the journey as Station A -> Station B by train followed by express replacement bus running between Station B -> Station C and then continue in reverse direction from Station C -> Station D. While tapping off at destination, I noticed that we were erroneously charged for two separate journeys (A -> B and C -> D) instead of a single journey from A to D. I feel this was due to the timegap between tap-off at Station B and tap-on at Station C exceeding some predefined threshold, which was due to rush + extra waiting + travel time for taking the replacement bus to Station C.

I raised a fair enquiry and managed to process refund without any issue but I was wondering how many other customers were impacted by this especially given that there was lot of maintenance work performed during Christmas -> New year period. Typically, I don't notice fare being charged everytime I tap-off but just happened to notice it at that time. In most cases, this may not be an issue but it is good to be aware and check fare being charged while taking replacement buses as the system may not be smart enough to handle all possible scenarios and such errors need to be fixed manually.