A caller who asked a question at the end of a call could be hung up on without an answer. Someone who had just finished making a booking and said “thank you very much — is this all done now then?” had the line end on them. They were asking whether the booking had actually gone through, and the phrase “all done” inside their question was mistaken for them saying they were finished.
A question is never treated as a goodbye now. If the caller asks anything at all — whether it is booked, what happens next, when the email arrives — your receptionist answers it and waits. Saying goodbye properly still ends the call straight away, so finished calls do not sit on the line.
The goodbye itself was also being cut off. Your receptionist says “thanks for calling, goodbye” before the line closes, but it was only waiting a fraction of the time that takes to say, so callers heard it clipped or not at all. The longer the message, the more was lost — the message about a call running over its allowance was losing most of itself. The wait is now worked out from the length of what is being said, so every ending is heard in full.