I cant wait forever

I had car finance that was settled over a week ago but for some reason it was never closed, I then had to also pay an installment on a settled account and was promised a refund but it will soon be a week of waiting. The initial day (today) to have the matter resolved and nothing happened and I was also promised a call by the consultant responsible for this case, needless to say I am still waiting. The new settlement after the account closure was showing a negative (-) amount which grew after the last debit order went off and they claim I was not meant to see that negative figure, meaning they want to make it look like it is not part of the money due for refund. I am certain they already made some positive returns in terms of interest and I know that I wont even see a cent of that