Hi Ang.

I can only summise that the mattress you have is unsupportive for your needs and what you are trying to do now is to put right what should have been there in the first place.

Support and comfort should go hand in hand and you will find it very hard to make an unsupportive mattress - supportive.

Placing a plywood or pegboard sheet on top of your sprung slats will go someway of aiding support.

If you are contemplating using a firm mattress under your current mattress then this would have to be in relatively good condition to offer the support required.

I would look at on-line companies that cut foam to size and get a piece of very high density foam cut to the size of your base, this will be cheaper than buying a firm mattress to put underneath your current mattress.

However, it does seem to be a shame that you have to go to this length to obtain the support you require.

Kind Regards Gary