Cheated by Standard bank Insurance

I have recently taken a loan on my house with standard bank. When the lawyers sent the documents to the bank, they also included proof that I already had insurance on my house. Three people from standard bank insurance telephoned me and I told all of them that I did not want insurance as I already had insurance. In spite of this they debited my home loan account with two amounts of R868.63 and R169.08. After e-mails and telephone calls,they agreed to cancel the insurance but seem to be unwilling to reverse these amounts although I have requested them to do so. I find this completely unacceptable as I have at no stage agreed to the insurance. This is just a way of making extra money at the consumers expense.