Deducting more than they should

Myself and my husband purchase a car in 2019 with standard bank. And with the first installment they deducted more then they should. We then went to the bank and they said it's insurance that they deducted (bare in mind an installment we didn't ask for or signed for as it's states on the contract ). We then took the contract and they could see that we didn't agree to it and we have insurance at outsurance. They then said they going to sort it out and refund us. For the whole year of 2020 up until today they never sort it out and still deducting. Up until today we calling going to the bank (bare in mind using our airtime and they puttingyou through and on hold most of the time. ) taking time off to go to the bank. And up until today nothing is happening. We so frustrated with this bank as we don't know what to do anymore as they deducting month after month more than they should.