Took 3x installments instead of 1x, no response or refund

I did an early settlement through the app, on that day the app struggled, so the settlement was done twice plus on top of that they ignored my early settlement and still deduct the last payment as per original purchase agreement, now I paid 3x instead of 1x. I emailed them twice, no response, the chat online dont work, the robot dont understand, tried to phone 3x, the answering machine just divert you to other channels instead of a person that can assist. This is my 3rd purchase, but it seems early settlement is a mess. Now I reported it to my bank.