Insurance claim denied

On the 1st of October I took a contract with Vodacom for a cellphone and I made it clear that I want it fully insured and so it says on the contract. Now my phone is damaged beyond repair and I tried to claim and they tell me I am not insured or they haven't been debiting the insurance money, and I was not aware because i thought everything was done right. Now I suggested to them that since I have not done anything wrong I backpay the 3 months and excess due and they replace my phone but they decline. Now I am stuck with a sim card that's got 21 months to go and no phone