razzy4raz - thats not too big, there use to be some iron on material patches, maybe you would get them from a Haberdashery or ebay. Or how about a home repair, cut a small piece from the inside of your leg hem for example &
handsew or glue with material glue from a craft shop, or maybe you have a friend that owns a sewing machine that will do the job as invisible as possible? What about waterproof magic markers?
Hi Raz. Dylon do a fabric colour stripper. Depending on the fabric, you could use this to strip the colour back to a lighter shade, then buy a machine dye to re-dye the fabric.
This won't be very useful on synthetic fabric or if your trousers.
Alternatively you could buy fabric paint in the same colour? They do pens and small bottles in a variety of colours.