Who do I believe M-Sure or Discovery?

Please assist in a response. When I phone M-Sure they tell me the merchant I am using to repair my car is approved and there is no issues with this merchant. However, when I select this Merchant through Discovery Insure Discovery tells me that they are not approved by M-Sure? Who is giving me the correct information? I am sitting without a vehicle as neither of the two is giving anything concrete? I need this resolved ASAP.