Standard Bank Home loans~ A ****!!!

I have a home loan with Standard Bank, for a while I was paying through debit order. Then later changed to paying through the employer. Months later they debited my account even though my employer paid. I then asked for a refund, they paid me 3 times the amount I asked. Then when I enquired about the money, they said it’s money that is due to me since I pay extra via my employer (it didn’t make sense but I took it anyways). The following month they debited me again and I called to ask for a refund, they said they can’t give me a refund since my home loan is in arrears, the money that was paid in is now acting as a loan. I kept on calling to find out what’s the way forward because I never asked for a loan, it was a back and forth of calling and going to the branch twice a week for 2 months. Suddenly the home loan repayment went up, then I enquired they said it’s the money that was paid in as a refund. My account is in collections because it’s in arrears. I asked to pay back the money with no interest they refused and would rather add the amount of years to my home loan.