Harrison Beech replacement

In the past five years we have had two Harrison Mattresses, the first contained a manufacturing defect, where part of the ticking was missing. The bed was uncomfortable, but Harrison and the seller weren’t that interested, and suggested the bed would “Bed in”. It didn’t, and eventually Harrison sent their expert to see the mattress, who said the mattress was at fault. However, Harrison said that as the mattress was then over a year old, they wouldn’t replace it for nothing, and made the seller pay the difference between the price we paid and the price of a new mattress, and also charged them more due to “wear and tear” as the mattress wasn’t new. Whatever, we decided to let them have another chance, and chose the Beech Mattresses (Super King, Zip & Link in Firm). Sadly, both of us don’t find the mattress comfortable after a couple of years, and are looking for something different. We are both under 70kg (11 Stone, 154lbs), and have come to the conclusion that something nearer a soft mattress is more likely to suit. My Wife finds that if she tries sleeping on her side on the Harrison, that her hips sink in about the right amount, but her shoulders don’t sink in enough, making it uncomfortable, and seeming to cause neck and shoulder aches (she feels worse after a night on the mattress than before going to bed). I have started to get shoulder and neck pain recently, and despite the fact that I have always been able to sleep on pretty much any bed, and very rarely find any of them uncomfortable, am beginning to wonder if age has finally hit home, and I need a particular type of mattress. We have been looking at the idea of a Latex Mattress, but are wondering if a combination of Latex and Springs would be better. We are not interested in memory foam, and really don’t see why it became so popular. Do you have any advice and suggestions for what might suit?