Minor repair of creasing leather - Recaro yellow seats

On my now passenger seat (was originally drivers) suffers some creasing and it makes the leather look lighter there in brighter light

Here is original picture of when I first put them in, haven't taken more recent ones close up yet of the creases - you can just about see the creases but doesn't look bad there

http://www.briskoda.net/forums/gallery/image/5119-dscf0482/

Is there anything recommended to repair this? Would one of the yellow colour pens from ebay be okay

I can get the seats covers off ( need to weld the support frames properly on anyway which means removing the seats ) and was thinking of gently approaching the hairdryer trick for the creases themselves for the stretched leather - but I think it may have lost some colour when they creased?

I wouldn't rule out having them repaired also (just the one passenger lower base or maybe drivers also so not much work to do). They were in pretty neat condition when I got them for the most part, good for the age of them anyway.

Thanks in advance