This particular IKEA-Haarlem shop diced not to acc...

This particular IKEA-Haarlem shop diced not to accept returns in case it was assembled!!!!
Bought few chairs. Assembled them at home then decided to get different ones. Disassembled them and put in the original packages. Brought back to the shop and have been told that it s not possible. The reason is it is the rule of this shop. They said this rule exits for about a year, which I doubt. I asked to check if IKEA in Amsterdam has the same and it turned out it not. Tried to get any reason why this rule exists in one shop while the other does not have it. Was told that this decision is made by main director of this shop. The official IKEA return policy does not have this rule. What is going on?! I am very frustrated with this. This shop is loosing me as the customer I am afraid.