Phew! Kudos for fighting it through.
This happened with my driver last year. One month after he started working for me, his icici account got frozen. He was informed that there were too many suspicious UPI transactions and that he should open a current account and not savings account. This happened as our driver would make misc. purchases like groceries for me and I would GPay him the amount immediately. When the driver explained this to his bank, he was asked to submit an an employment letter from me, and a letter from me addressed to the bank manager explaining the case and I also wrote asking them to verify that indeed all UPI transactions are small amounts < 5,000/- . His an account was unfrozen pretty soon.