and get the ed psych to amend the iep targets to reflect letter strategy.
what are his iep targets incidentally?
are they 'smart'? if so, the school have to have discussed with you how they are going to help him to reach them - are they actively helping him to reach them?
if his iep is well written, you can use that document to point out what they should be doing. if it isn't, ask them to rewrite in accordance with 'smart'.
and call the area inco. if he's got an iep and has been externally assessed (and, to be frank, excluded), he should be on the sa+ list and she/ he is probably aware and has seen him. call her/ him and explain that you seem to be getting nowhere - of course you and the school both have ds's best interests at heart (lying through your teeth is necessary at this point, although tbh they probably think they are acting in his best interests) but that somewhere the issues are not being resolved. ask her to attend the meeting with you, the senco, class teacher and ht at school (and ed psych if you can persuade...). does he have social targets?
has he got two ieps running? one for his giftedness and one for his sn?(with behaviour targets and social targets? or are they esteem targets?)
this can be sorted out you know.
but ultimately i think you are in denial about the amount of disruption he's causing. there are no end of kids whose parents can't get them assessed for love nor money. a child who has been assessed, been given additional support, and still managed to get excluded is actually a child in need of more support, or support of a different kind. so get on the phone and move it up a notch. i'm not trying to be mean - and i know schools aren't perfect, but i have never heard of a school taking so much unnecessary action over one child. there just isn't the money in the system for it.
have you spoken to the sn governor? or the chair of govs? they will be aware anyway because of exclusion - i'd be on the phone to them as well.
and it may be that (after all) you do need to start getting other parents to go in and complain, and demand that more support is offered to your child so that the education of their children is not disrupted any longer. (their words lol, not mine.) you have to get them on side pretty fast now, or they'll just be demanding permanent exclusion...