IMO the seller and your local specialized dealer are both at fault.
Specialized SA are anal and in a super anal way about all their frames and bikes that they sell.
So much to the point all it would of taken from your specialised lbs to send a email with the frame barcode to head office in stellenbosch and they would of immediately got a full history report on the frame before you bought it.
Everything from what shop sold the bike,who was first owner,was the bike in a wrightoff or repairs.They keep that information on every bike/frame they ever sold.I was in the same situation buying a frame on the hub and went thru the process.
Specialized came back to me and could say bike was bought at X shop,was repaired by CBR on X date etc.
When I questioned seller about the bike been repaired he just told me that’s the first he’s ever heard about it…..
Second thing there are a number sellers on the hub selling “repaired “bikes and frames.I’m pretty sure they got a contract with insurance to buy back ,repair and re sell on hub.What really gets me is that they NEVER indicate in any of their adverts it is a repaired that is for sale.
My advice is get the mail off to specialized with frame barcode,get frame history,if you can prove seller knew it was repaired and didn’t tell you,take it further.