Proof of refund

I have a short fall cover I claimed with IUA insurance and it also has a paint tech auto body warranty with M Sure insurance...IUA has been waiting for Msure to send them a prove of refund for over a month now so that they can finalize my claim.I have called Msure insurance for over a month asking for the prove of payment and 4 weeks later I'm still waiting...it's Frustrating to ask for a small document for a whole month.i need my claim to be finalized and Msure Insurance can't provide me with what I need...I have been patiant with them but this is unacceptable.