Bad service, I want my money!

I called in May to remove a few things on my policy so my premiums could be cheaper, this was down, this company decided to debit me on an incorrect date (22 May) when my date is the 25th obviously debiting an incorrect amount. I spoke to a lady who confirmed that she will process a refund. I told her to leave the refund and allocate the credit so that the next debit order is a difference of this refund due. Again I was devoted on an incorrect date in June (24) and the credit was not allocated. I then called to cancel the policy completely. I was told the refund will be received within 7 working days. It’s now the 7th of July and I have not received my May nor my June refund. I keep calling the call Centre, and they promise me callbacks and that refund will be received. I want my money!