Horrible RCS

I have a loan account at RCS and I wanted to move my debit order date, I was asked to pay a double installment which I then did. After paying this. They keep deduction more off my account and not ducting this on right date. I have to phone their offices every month since May and this problem is not being solved does not matter how many times I complain. I receive no answers nor good service. This company is terrible.