I've been informed like a hundred times about that already.
The problem is that you cant unseal it, but until that part everything is working perfectly.
First of all, I will try to fix this by finding the NPC from the L2J files. If I wont make it, there are two possible solutions.
1) To make the NPC look like a GMshop. (The only difference will be in the code)
2) To make a trader, who earns Foundation items and give you back normal items with some adena.
I'm keen on the first one.
/djNio