Memory Foam 1250 Mattress, Medium Support

This mattress is definitely not medium support. I have owned a mattress containing memory foam before and I sincerely wish I had kept it however as I was updating my bedroom, I bought the above mattress from Marks & Spencer thinking that it would be similar. This mattress is awful, it's like lying on a board and I have woken up every night in discomfort because it is so firm. It has not softened over time. Marks & Spencer customer services sent out a FIRA technician to examine it but he stated that he could only examine it for faults and could not rate it for firmness. Marks and Spencer customer services say that as the mattress is not faulty they will not accept the mattress back, they cannot seem to understand that the mattress is not as described, i.e firm and not medium support. Interestingly, there are 5 reviews of this mattress on their website which say the same about the firmness but these are all old reviews. I tried to post a review but apparently, it didn't meet their terms and conditions for reviewing! Very, very disappointed in both this mattress and Marks and Spencer customer service who are unwilling to even investigate my claim that the mattress is not as described.