Not so important person

I am just at a loss for words. I tried reversing funds on the app, the amount is too big, I spoke to a banker via the app, they cannot assist and I need to call the call centre. I call the call centre, spoke to a bot, debit order reversal is unavailable. I need to reverse funds. I paid the money at their branch who debited me, and they still debited, thus me requesting a refund. Please assist urgently.

Thanks