I'm back. Call me a big softy, but I wouldn't bring Robot Wars into this at all. Just go and have fun. After all, you've got the tickets already and he's probably been telling all his friends about it for ages. If RW was a long way off and you were at the planning stage, then the threat could be a good option. Anyway now it's too late, it's too good to miss and he'll think you're such a mean mum if you stop him going.
Yes, you've got to get firm with him about his rudeness, but find some other way. I'm awful at getting firm, but since having a stroppy son, I've got a bit better. I just don't have any natural air of authority, though.
Leading on from what Janh has just said, first talk to him about his holiday. Be really interested and find out what he enjoyed and what he didn't. Try and get him to joke along with you about the latter like did granny try and give you her famous scrambled eggs again?. Then in a neutral tone of voice, mention that you heard he said 'shut up' to his grandmother one teatime. Find out his side of the story. There's no way you can let him off the hook, but if it was me I'd say something like ' you know how much I hate 'attitude'. It's rude and people won't like you if you behave like that. You won't get invited to your friend's houses or go on sleepovers. Do you think I'd have one of your friends to tea if I thought they'd say nasty things to me? I don't care if your grandma was nagging you etc, you don't say those words. If things are really making you cross and you can't think what to do, next time you ask to phone me and I'll talk to grandma.'
The I'd probably have a firm talk about his behavour now he's home, and say the treats you have planned for the next few weeks of the holiday depend on him being good. Be a bit mysterious about the treats (that leaves you with room for manouvre), but very specific about potential punishments (so he knows where he stands)like taking away his gameboy, pokemon cards, bike etc.
Coincidently, my 7-year old is due back from his holiday with his grandparents this weekend. They live near the near the beach in Devon. We've phoned each night and the feedback has been uncannily positive - as usaul. Nanny, grandpa and son seem to have one big mutual appreciation society going on down there, fuelled by lots of homemade puddings. According to nanny, son is a joy to have around, even asked if it was time to get up at 7.00 am one morning, and obediently went back to sleep when he was told that it was not. WHAT is going on down there?? Who is this boy paragon?? I don't put this down to to our good parenting. Why doesn't he behave like this at home?
I get plenty of the kicking doors, swearing (I'm sad to say), throwing his shoes around, answering back behavour. But it has got a little better as he grows up. I went through a really rocky phase with him, smacking him, saying 'no' and shouting at him. When he's dong something unacceptable my first instinct is to send him to his room. And he always refuses to go. He's too big to be carried up, so I have to theaten him with a punishment, just to get him to go upstairs.
Anyway, I'm probably teaching you to suck eggs, but here's what seems to work (a bit). I definity feel that many of his 'strops' are caused by him not coping with peer group pressure too well. Peer group pressure seemed to get worse and worse for him from 6 onwards. That may explain why he's so good with nanny and grandpa. He's can be bad with boys his own age They all seem to get so over excited with lots of swaggerng around, showing off and being 'cool'. He's also not that good with older girls - they are too adept at winding him up and teasing him. After playing with them he does have a tendency to take it out on mummy by having a strop. And the more he's in an arguementative, competitive group, the more the attitude seems to stick. He's can be a different child with girls of his own age, however. Much more laid back and easy. Goodness this sounds so sexist. It's just reflecting the way many boys and girls seem to play differently.
Anyway, I've had to rein him in a bit lately, by rationing the time he gets to play with some of his friends, nice children in themselves, but they bring out the worst in my son. I havn't told him I'm doing this, because it's not a punishment as such, just a slight adjustment to his social life, avoiding situations where I suspect he'll start misbehaving - and slighty upping the time he spends alone with me.
Also, I've followed that positive parenting adivce, with atttention and praise when he's been goodetc etc. It really, really, has made a difference. I'm sure you know all that stuff so I won't go into it now.
Running out of time...
Good luck, Rhiannon!