What to do!? I have black & red interior & it was looking tired. Some cracks & scuffs etc. I came across this before & was quoted silly money to fix it. First thing I did was to add a moisturizer/cleaner/sealer all in one. You can buy this kind of product online/halfords-for extra cost, or other places. once I'd done that I took a route I tried years before. I got online(this for my 206cc) & ordered a near on colour match. Black-not too hard to find but the red took some time. Then I went carefully over the leather & it took a few applications but it covered really well. Buff it over, used kitch towel
to remove excess & buff it over again.

I then put on one more coat of the sealer etc & it came out really good. I can take no responsibility for your butt or clothes changing colour. Try it on one seat first, see what you think.
All the best.
206 cc 1.6 16v black 02 plate. Aka-cheeky charlie.