Basically, it depends on how long it takes to do. The more that is changed, the longer it will take and the more it will cost. I charge £20 per hour. A simple repair of a tear or blemish will take about 30 minutes, major changes could take 2 or more hours. 

I have a minimum charge of £10 and collection and/or delivery is an additional cost.

A simple scan, where I do no work on the photo, just give you a computer file and your photo back, is £1 for any size up to 8" x 6", £1.50 for larger. Again, any delivery costs are extra, and these costs presume you supply the empty media. I can supply the media for a little extra.

I'm confident you'll be happy with my work, so I'm prepared to offer a guarantee: if you're not happy with what I've done, don't pay for it. You don't get the updated picture though!