Maddison corner sofa

Bought the Maddison corner sofa and two seater sofa and took delivery in July last year. I complained about the quality a few months ago regarding the cushions are flat even though I paid extra for the upgrade, I also have a chaise I can’t sit on as your legs slide off it. I complained to Marks and Spencer’s and they sent a gentleman out from Castalan to look into my complaint, It took me to call Marks and Spencer’s to be told they would look into this as I hadn’t had any feedback after his visit, this is the email response I received, not even a phone call to discuss further. I understand you were unhappy with their initial outcome and I have reviewed the report that was completed following the visit to assess your sofa. As you know, this concludes that there is no manufacturing fault , but I appreciate you remain unhappy with their appearance..

The report states that the issues have been caused by the affected seats being used the most, and not turning or swapping the cushions around.”
I assured them that I do alternate the cushions and air them but this sofa is not fit for purpose I have sent numerous emails to M&S and now told to go to the ombudsman which of course I am