Overcharged by Nedbank

Approximately 8 years ago we were granted a homeloan by Nedbank on condition that we also took insurance cover on the buildings. Nedbank bundled the homeloan and insurance cover into one monthly amount and informed us that this is what was due monthly. 2 months ago while talking too a representative from Nedbank i was informed that the insurance cover i have from Nedbank, does not have to be a Nedbank policy but an insurance policy from any insurance company. So i shopped around and got the equivalent cover from First for Woman at R280 per month. Now my policy that i was "forced" to accept as a stipulation from Nedbank was R1050 per month. Not only am i very upset that i have overpaid by approximately R75000 over 8 years for insurance but that i was never informed that i could get cover from any insurance company at the time of signing the deal. It was inferred to me that we had to accept their insurance and was all already in place at the time of signing. To really top off a great experience, i have tried to cancel this insurance, to no avail, I have phoned and emailed the insurance department at Nedbank over the course of 2 months and my policy is still not cancelled. Even though I have submitted all the required documents repeatedly. A very sour experience Nedbank, I hope you attend to my complaint promptly and rectify this overcharge.