State Bank Of India [SBI] — credit card billing

Address:

560010

I had credit card bill of rs 40693 for september 2019. There was refund of 12000 to card after the billing cycle and paid the remaining credit card bill by deducting 12000 since the bank had already received the amount. But i have been charged 2500 of financial charges stating that i din pay entire 40693, when contacted the customer care about this they were so rude and stated that refund is not applicable as payment. When bank have already received the 12000 amount why should i pay the 12000 extra as bill payment.
I want my financial charges charged reversed.