Hi aladrieth.
And welcome to our Mattress Forum! 
Sorry to hear about your box spring foundation failing … I’d be curious to know why you think that solid foundations would not work for you? What type of mattress do you sleep on as this is an integral part of how the entire sleeping system serves you. “Box springs” are more important than many people realize as depending on the type they act as shock absorbers (have some give in working with the mattress instead of against it).
As far as solutions go I’d start with the manufacturer of the mattress you currently own and ask for their recommendation for warranty reasons. Was your mattress part of a sleeping system with a flexible slat foundation or with a “box spring” or with solid wood slats (most of them are)? The “box spring” terminology may be misleading as it comes from far back in the “old days” when they truly were springs used under a mattress. Some manufacturers design their mattresses to be used over a flexible or tension adjustable slated foundation which is an active and important part of the complete sleeping system (although again this is usually with thinner mattresses). This type of foundation is more commonly found in Europe so you are correct that you’d have fewer options available. What is your budget range? And finally … Canada or US?
We’ll be moving your post shortly to it’s dedicated thread. Hopefully, someone who has had some experience with the Berkeley Ergonomics Suspension Foundation will chime in. I am not sure if you had a look through the Foundation thread here but this is a good place to start your research … specifically, post #3 linked to in that thread.
Phoenix