Insurance claim

I took a cellphone insurance with Monitorsa at Foshini when I was buying cellphone in August 2023. It was a single sim and I was buying it for my sister. However she was ****** and the phone was ******. We were asked to blacklist the phone but it was not possible as the simcard the was used on the phone we got it from the street vendor. I was not advised not to use the simcard that was not registered on our name. We were sent from pillar to post regarding the issue. Telekom is refusing to blacklist the phone even though we have proof that we have been using the number for a very long time.We were asked for a lot of things and at the end it was told my claim has lapsed and they can't process the claim. But Monitors a still deducting the premium amount. Pls help