ABSA Insurance rejection

We bought our house and bonded it through ABSA many years ago. At the time we were forced to include ABSA insurance as part of the deal. Our pool pump stopped working early in May and we claimed for this. On 18 May we received a rejection of this claim as the pump motor has been damaged by an "overload of electrical voltage caused by load shedding"

I find this suspect as NOT a single other electrical item in our house has been damaged at all and I assume that a surge would have led to multiple sensitive electrical items failing and not just something as robust as a pool pump. My question thus is why am I forced to pay ABSA for my house insurance and cannot move to another insurer that honours their policies.