Unfairness treatment

I have a cellphone contract and Insurance with Mtn n what happened is my phone got lost in a train, before de incident I wanted to check address of were I'm going on my emails n didn't have Data so I inserted another Sim card which I gave a consultant as a second number Dat had data unfortunately de fone got lost same time. Now dey declined my claim as their policy says de simcard need to be In a fone or I should notify dem if I change de simcard but it's unfortunate cos it was an agent matter n I didn't have aitime to fone dem. It hurts bcos I insure a cellphone but now I can not claim it bcos of a simcard. De sad part is Dat dey continue deducting money for insurance from my account. Plz assist me on dis unfairness policy n treatment