C Surance owe me

I took my first cellphone insurance June 2015 when I bought my first phone. What I was not told was that I was supposed to cancel the insurance as soon as I finished paying the phone in 2017. They carried on charging me monthly and I thought it was normal. January 2019, 23rd, I get a sim card deal and I get a message saying I have cancelled my insurance. To my surprise I call customer service and all I was told was "I'm sorry but you should have know that you should cancel your contract after finishing paying the phone as prepaid phones are not covered ". No offer to pay me back, just apologies I didnt need. If it wasn't for my current contract I would have left cell c