any way to mitigate heat from memory foam mattresses? (Luna Memory)

[Datafan55]

New mattress this week. It's rather too firm for my back (despite being softer than most in the showroom), and it's with memory foam so I'm waking up after a few hours absolutely boiling.
Does anyone know of any ways I can mitigate the heat without the faff/expense of trying to replace it?

It's this model (not from here unfortunately so no trial period);
https://www.mattressman.co.uk/product/silentnight-luna-memory-mattress-p194601
When I asked about memory foam and heat in the showroom I went to, they said 'not aware of any issues'. I am a bit annoyed about this.

The diagram on the mattress might indicate it's a built in topper.... so maybe I could flip it? Or it's built in.

The only way is to return it to the shop immediately and buy a normal pocket spring mattress.
Memory foam mattresses are horrendous. Like lying on hot wet sand. All the man made materials make you sweat like a whore in church, you'll end up with a Turin shroud like outline of sweat.

They don't have a trial period at this shop unfortunately. Plus all the ones in there seemed to be fancy layer this and fancy layer that (with the best firmness at my price range being this one).
I have just emailed them to see what they say.
#boiling

I have heard of cooling mattress toppers. Never tried one but could help

I think that's what I'm hoping for... In the hope it would cancel it out. Yuck! It took me ages to choose this one as it was.

Mine is memory foam with cooling gel in from Jysk..Best £800 I've ever spent.
Not hard either.

jysk.co.uk/bedroom/mattresses/foam-mattresses/foam-mattress-gold-f110-wellpur-double

I'll have to bear that in mind if I have to buy another.
Hoping I might be able to add a separate cooling topper first though :-).