Bought a 3 piece settee

Hello I recently bought a 3 piece setee, it was a floor model and I got 30% off because they were moving shop.
It is a recliner leater settee and I noticed after getting it that one of the armchairs would be unsteady when in recline mode, i.e it would rock a small bit from side to side if you moved, and it seemed to be leaning a bit to one side. I said to myself I must adjust the stands on the bottom to level it up. I have it 2 weeks now and I looked at it last night and it is not adjustable.
It is 2 inches lower on one side and seems to be an assembly fault, what recourse do I have with the shop as it was a floor model, They did not say it was shop soiled or anything.
I know I would have good rights it it was new but am unsure as it was a floor model.
I have not approached the shop yet as I want to start on the right foot.
Thanks

By floor model I assume you mean it was the one on display in the shop and surely it was new (not secondhand). Were the wonky legs pointed out at the time of sale and was the discount on that basis. If not and the goods are faulty you should have your full rights under the Sale of Goods Act. ie. repair, replacement or refund.

Goods not of merchantable quality