Lost progress after linking account

I've played Apex Legends for years on PS5 and my Sony account. I wanted to change my EA account, linked to this PSN one.  The linking/unlinking button didn't provide any warnings that I would lose all my progress, all the money I've spent on this game. So once I've identified that, I wanted to change the link back to the original EA account. But now unlinking is blocked for 6 months (!).

I've contacted an online support of EA, but they couldn't help at all. What's the point of a support team if they can't help with any issues related to account progress? I'm really disappointed in EA's capability of solvint isssues like that. The support didn't even try to check my ownership of this profile. I have every proof of ownership for this profile, but there are no options presented by EA to show it, as well as any compensation for my frustration with using EA's product.