Need help with Borderlands2 and shift account

I have having issues liking my BL2 (pc) to my Loot the World account. Gearbox says to try and unlink the accounts and relink them, but I can’t get linked to my shift to my Steam account to begin with. I get the message “This platform ID is associated with another account” but I only have the one account. So I need help unlinking my accounts. Anyone have a clue? I had one contact with gearbox support and they haven’t replied to my reply after 10 days.