Vodacom Insurance don't want to fix phone

My cell number have been with vodacom for about 3 years now. About 3 year ago my fiancé took out a 2 year contract for me with Vodacom which included a Samsung A3. When it was time for an upgrade we stayed with the same number and just upgraded the package & phone to something more expensive - the LG G6. At that time, my fiancé's was waiting for his company phone so used his vodacom number and put it into the LG G6. About 2 months later the phone dropped and the screen cracked. We have Vodacom insurance on the LG.

We sent it in for repairs and now they refuse to cover it because another sim card with another number was put into the phone, even though it was a Vodacom number. This was not explained to us when we upgraded the phone. I am not very happy with this. I can understand if the number for which the upgrade was, was not being used anymore, but it is. The current number for which the upgrade was is still in use.

Vodacom now wants to charge us R3500 for a screen replacement although we have insurance just because another sim was put into the phone.

So in other words, when you get an upgrade, must you just through the old phone away?

Also no one explained to us regarding the fact that you are not allowed to put another number in the phone.