ABSA kosting me R24 000

I had a ABSA homeloan insurance component on my bond which I cancelled as I insured the property with my current insurance broker. The amount for the ABSA insurance was debited to my bond to the amount of R4800 on date of registration. I cancelled the policy on 20 October 2015 and have the confirmation thereof. ABSA insurance however never refunded the pro-rata portion of the insurance to my bond. I noted that today 2 Feb 2016 and followed up and aparantly now they will escalate it and make work of it. If I did not follow up, they would have probably got away with it for ever! This whole mistake by ABSA is however going to cost me approximately R20 000 in extra interest that I will have to pay over the bond period!!!! this is ridiculous! I need this insurance money as well as the extra interest that I will now pay to be refunded to me.