Damaged Launge suite and promises of collection not met including bad service

I bought a 4 piece launge suite on the 2nd May 2017 at OK furniture in Motherwell, I noticed that the two sitter was sagging . I sent my sister to report the matter to the store in July hoping that they will come and inspect the damaged good and do something about it, but they never came. In august my mother went to the store to report the same thing and she was given the phone number of the salesman. They requested pics of the damaged launge suite and we sent them. Still they did nothing!

I kept sending messages to the salesman asking for their plan and on the 21st of November he sent me a credit note from the supplier (Exchange note 083 from Component Manufacturers), advising that when one of their trucks are in the area, they will come and take the damaged launge suite (What is that!) and exchange it with the one that was going to come from the supplier.

Now im still sitting with the damaged launge suite that I noticed within 3 months of purchase, and was reported on time to the store that did not care.

The service that I received from OK Furniture in Motherwell is the worst ever, and they do not care about customers unless you are bringing them a sale, after that the customer is nothing.

What I want now in a brand new launge suite or my money back.

Kindly assist, its been too long now