Giving them estimated grades isn't particularly fair either given that there is no appeal against them (unless that has changed) Mrs Q reckons she gets asked a couple of times each year if she will go through a GCSE paper by a parent who thinks that their sprog hasn't got the marks they should. Certainly I remember last year she was really pleased that she found a couple of marks that on appeal was enough to boost the kid from a 3 to 4 and from a fail to a pass.
At the other end of the scale we have our own 18 year old smartalec who is expected to and will probably get top grades, She's miffed that she can't prove she has earned them.
A retake is the only way to change them. I am really annoyed that there is no appeal process, particularly because our subject has gone from a 'mandatory' subject last year to one of 'choice' this year. Results would have been much better but OFQUAL are basing them on historic data, so am worried some of our pupils won't get what they deserve.