Leather seat repair / colour filler ?

Anyone had any experience of very good quality repair product for something like bright (yellow) recaro colour concept?

I've a few patches I'd like to colour in a bit better so they looked almost like new, (creases in the leather that make it less yellow, but not ripped or cracked),

and as I need black and yellow, the black could also come in handy x2 as I have another car gifted to me (160vvc mgf) low miles but the leather could do with a bit of love in certain patches like getting in and out the car (when I ever get the car that is).

Its very moderate repair, not on the extreme side but they do look "used".

Not badly so, but I would imagine with not much love could look brand new

( I plan to refiit again anyway as I originally never had an ARC welder when I originally "araldited"/taped the support bars and I do notice they creak on the passenger side when wife gets in - something easily solved).

I don't want to waste money on something that isn't perfect for the job....if I could get something exactly matched....or someone else to do a perfect job on it is another option.

As a perspective on how much I'm prepared to pay they are 2nd hand already I don't put unlimited price on that though - seats were sub £200 as it is!

( well just over £200 + £40 donors + fuel - £150 selling original seats so not a huge amount over £100! )

Any ideas please - thanks all