Hi..I weigh exactly 14 stone and my wife 8 1/2 stone. Over the past year we have had 2 differing superking mattresses-a sleepezee approx £400 (medium firm) then a Hypnos £970 (firm). We have a drawer/divan base (hard base, not sprung). Within 2-3 months both mattresses have shown 2 dips approx 1-2 cm both sides where we sleep-these are apparent when you pull a sheet tight. We turned both mattresses as advised but this has made no change. I even try to lay in the middle where the slight raise has formed to try and flatten it down but it doesnt seem to have any effect! I know find that with the Hypnos firmer mattress that we have had for 3-4 months that I have a lot of shoulder ache/pain which i am now wondering is this due to the firm mattress? So, My questions from this are:1:- If I bought from you-WHICH superking mattress would you recommend I have (I have seen one which seems to fit what I am looking for because your website is very clearly written and very educational)-and would your recommended mattress sag in our 2 positions-and if so would you replace/refund within 2 months?2:- Do you think my shoulder ache/pain is due to our current firm mattress?I look forward to hearing from you very soon,Thanks Kevin