I ordered a large heavy product off ebay, all is good except one small bracket which is defective.  

Obviously neither me or the seller want to return this massive expensive item just for the sake of 1 small cheap bracket.  It's quite unique tho - not something i can just buy off the shelf at a hardware store.  I contacted the seller, and they agreed to send me a replacement bracket.

Problem is the replacement comes from China, and I need to allow 1 4 days for delivery.... which takes me outside my 30 day guarantee.  So what do i do if the part never arrives?

I tried opening a case but my only option is a "Return", which I don't want to do, i just want open a case to freeze my 30 day guarantee to allow the seller the extra time to send the missing part.