"You don't have access" error - unable to play purchased game

Leaving this here in the feedback section as I have already requested help for this issue from EA support and have been unable to reach a resolution.

I recently tried to download and install The Sims: Medieval from my EA Play library. This is a game that I purchased almost 15 years ago and originally redeemed and installed on my Origin account before the migration over to the new app. Upon trying to download it, I recieved the following error: 

"You don't have access. We've cancelled the download because you don't own this game. To play, go to the Game Hub to get the game."

This is despite the fact that the game is listed in my library and my app itself states "Standard Edition owned" - how can I not own the game when the app is telling me I own it?

I spoke to support and was told that despite still having my original disc, case and redemption code - which the support agent confirmed was indeed linked to my account - they would be unable to give me access to the game and I would have to contact the original retailer for proof of purchase. After so many years, do they really think this is a reasonable request to make? The retailer I purchased from no longer exists. Surely the fact that I still have my physical copy should be proof enough?

I'm really disappointed and frankly angry about this and will be taking it further. Just wanted to put this out here for anyone else who is having a similar issue. Even if you own a physical copy of a game, don't expect them to honour your purchase.