Multiple shocking service shortfalls from Discovery Insure

I was recently involved in a small accident. Amongst the items needing repairs are one of the rims and the side view mirror. Discovery are refusing to cover the rims as thy say that it is an after-market item and has to be inured for separately. This is absolutely ridiculous as they had photos of the vehicle when I purchased it and insured it and so they should have automatically included it in the insurance premium. As it stands they are committing ***** - they are charging me a monthly premium on a fully comprehensive basis, by definition including rims, and yet those rims do not exist. They must therefore refund me the pro-rata cost of the standard rims since the policy started, as they are charging me a monthly premium on an item that does not exist. To make matters worse, the car comes standard with a folding side-view mirror, yet Discovery has only authorised a fixed mirror. The panelbeaters have contacted them on various occasions and yet Discovery do not respond. I guess once this is all over I need to move to another short-term insurer as well as move my pension fund and life cover elsewhere. Pity I can't rate them at zero stars which they fully deserve as there are 3 separate problems on a single claim.