Telangana State Road Transport Corporation [TSRTC] — Charging extra money on bus ticket counter

This happened second time in a row the staff at the airport bus ticket counter don't accept cash and when we do upi payment it never gets accepted. Meanwhile in my account it always shows credited to beneficiary and even after sharing the details they refuse to accept that we paid it and after the payment is done via upi, they accept cash and provide the change.
Is this some kind of scam going on the airport bus ticket counter. Taking extra money from passenger to some random account and then accepting cash.