TFG jewelery insurance - claim not paid

I went to American Swiss sunnypark to claim for my ****** necklace, which I gave the store assistant the relevant documents required now they tell me without the invoice the insurance won't be able to process my claim, after I bought the necklace I was never told to keep the invoice they just told me if I want to claim I only open a case and come with the affidavit to the store yet every month I pay the insurance. It's either they will refund all the money I paid to the insurance or the store will give them my invoice copy since they keep them for two year. I bought it last year Jan, so the store should have the copy. The TFG insurance should have records as well. I tried calling TFG jewelery insurance and their doesn't go through.