charging extra on top of a policy

After having a funeral policy with martins funeral parlour for years and not having claimed it yet, my grandmother passed away unfortunately yesterday, when we went there to submit our claim we were told that we have to pay R2000 for the grave yard and R2000 for the casket as they claimed she was overweight and we have to pay extra, this was never mentioned anywhere in our contract with them, so now we don't know what to do about that as we need to arrange the funeral and this is holding us back! Please help us.