Insurance on phone

I have tried now for two years to cancel the Fonesure insurance with no success as I cannot find any contact details for them. The phone was received from Cell C and although the phone has been ****** and the contract eventually cancelled Cell C cannot cancel the insurance and the bank cannot give me any details as to whom to phone. Why if you are a reputable company can nobody find contact details for you and even the cell phone companies have no details. I just want to cancel the Fonesure insurance on the lost phone as I have now been paying for 3 years without the phone and I could not claim a new phone as I could not contact Fonesure. The number I had did not work and now I have lost that number as well. I have never received anything in writing or signed anything with regard to this insurance.I want to cancel this insurance with immediate effect.