Non payment of claims

Bonitas BonCap, seems like they look for any reason not to pay for claims. I enquired about requirements before going for a mammogram and the agents kept reassuring me that the benefit is available and I can go to any service provider I like. Never was it mentioned that you first need to go to your GP, and it must be a GP on the list else the claim will be rejected. Claim was rejected because the GP wasnt part of the BonCap providers (even though she is on the Bonitas list) but the consultation for the GP was paid in full. Why make one jump through so many hoops for preventative care? Also note that your claims will also be rejected if THAT said GP isnt your nominated GP. As I said, any reason not to pay