Hi Goldendog,
Welcome to the Mattress Forum! 
Many also compare it to pulling teeth, but I hope I can assist with that. BTW, I actually like car shopping!
You certainly are due for a new mattress!
One thing you should always be aware of is that price and quality are not mutually inclusive when shopping for a mattress. Part of the problem when consumers are buying a mattress that is called a “latex” mattress from a major manufacturer is that most of the time it isn’t what could be reasonably be called a latex mattress at all. Most of the time, there is several inches of polyfoam above the latex (the type of foam that breaks down) and often the latex layers are hidden in between other layers of the mattress. Unfortunately, when people buy these, they believe they are buying a latex mattress when they are buying a mattress which has some latex in it. The old Spring Air latex (Four Seasons in the US) were the same way … a recipe for the body impressions that you are experiencing not because of the latex in them but because of the inches of cheap soft polyfoam that you were lying on and the construction and layering of the mattress. Even the versions with a latex core (instead of a polyfoam core) had way too much polyfoam above the latex.
The better options or possibilities I’m aware of in and around the Ottawa area (subject to making sure that any mattress you are considering meets the quality/value guidelines here ) are listed in posts #2 and #3 here .
If you’re considering online, use the experience and expertise of the members listed in post #21 here who are all very experienced and knowledgeable and specialize in providing the type of help and guidance on the phone that can help you make good choices (some of them are located in Canada and other ship to Canada as well). There are a wide range of latex options included in the choices there and I believe that all of them compete well with the best in the industry in terms of their quality, value, service, and transparency. There is also a list of online mattress sources for Canadians in post #21 here.
Naturellesleep is connected with Nature’s Sleep in Canada (see this topic ) and I would be very wary of doing any business with them. I don’t consider them to be a reliable or ethical supplier and I would put them in the category of “buyer beware”!!!
Personally, I would think that you’d be better off starting over with a new mattress, but if you are planning to remove and replace all the foam layers in your mattress and only re-use the cover and you are attracted to the idea of designing and building your own DIY mattress out of separate components that are purchased from one or several different sources then the first place I would start is by reading option 3 in post #15 here and the posts it links to (and option #1 and #2 as well) so that you have more realistic expectations and that you are comfortable with the learning curve, uncertainty, trial and error, or in some cases the higher costs that may be involved in the DIY process. While it can certainly be a rewarding project … the best approach to a DIY mattress is a “spirit of adventure” where what you learn and the satisfaction that comes from the process itself is more important than any cost savings you may realize (which may or may not happen).
Hopefully the links I’ve provided for online and local sources will give you a good start at finding a good latex mattress. Of course, please let me know if I may assist with other specific questions as you move forward.
Phoenix