Discovery Insure is very expensive and owes me money

I canceled my Discovery Insure policy because I could get a better price somewhere else. When I sent an Email asking if they could review my premiums, they said I was on the lowest rate they could offer. But when I phoned to cancel the policy they were all of a sudden prepared to lower my premiums - which were still higher, while insuring me for less. I specifically asked the lady I spoke to if I would get my Vitality Drive cashback and she assured me that I would, since I was still insured by Discovery until 31 October and I still paid for Vitality Drive for October. I put in R1000 worth of petrol in October, which means I should get back R500. Cashback is paid between the 10th and the 15th. It is already the 16th and no cashback!