Vodacom Insurance - Stay away

My contract is on my mothers name so she pays both our phones, on the last upgrade, we swapped phones on the upgrade but not numbers, the phone got lost and now Vodacom is refusing the claim because the sim card in the phone was her other number (the number I am using and have been using since day one, even before they offered her insurance).

So now basically it comes down to the fact that they offered her the insurance (telephonically) after we swapped phones, so they have been collecting the premium for the insurance but now according to them it was technically never insured? Yet we paid for the insurance for over a year (Iphone XS - Quite expensive to insure) for something that was never insured? How can they refuse to pay on the basis that a Vodacom contract holder of two numbers and both insured devices used the wrong sim in the wrong device???