We have Warren Evans “Superior” super king mattress, which is described as firm-comfy. Initially it was plush but supportive but after only two years it is definitely not comfy – it is extremely hard and the body impressions are pretty bad (with a large ridge down the centre). It is one that you can only turn end to end rather than flip over. My partner and I are both around 75kg and reading your website I think we simply bought a mattress that is much too firm for us? We are loathe to buy another mattress so soon – will one of your mattress toppers help add some comfort and also reduce the uneven feeling? I think we want something more substantial than a feather topper (which surely just squish down as soon as you lie down?) and I also tend to overheat so was thinking perhaps your Laygel option? Also is Laygel cooler than natural Latex or would they be similar? Which would be softer?
First and foremost, as you have a superking size mattress which has developed a ridge down the centre, this may be due to your base if this is a sprung slatted base. We have found that a sprung slatted base has a central metal piece which causes a ridge in a mattress. You could try putting down a piece of MDF or Hardboard to make this a more solid base and hopefully that would rectify the situation.
Also with a superking mattress, the centre of the mattress is not utilised fully which can also cause a problem and as the mattress you have is a non-turn, this is not going to help as you can only rotate it. One of you would be best trying to sleep in the middle of the mattress which will eventually flatten the ridge.