This is both shocking and not surprising at the same time - I believe similar stories are not uncommon in the industry.
I think there's a few options:
- Do nothing, and carry on as-is: not really an option is it?
- Leave. Good news is that there's such a shortage of chefs and head chefs in particular, I don't think age would be a barrier, plus would it be so terrible to start somewhere new?
- Fight tooth and nail for his rights (as already pointed out, the behaviour is illegal), taking a case etc. Stressful, and this is a small country, and confrontation is really a last resort.
- Try and improve his lot by negotiation. Stressful, too.
Personally, I'd look for another position to the point of getting an offer for somewhere that looks attractive (if it's very attractive, then just take it). Before accepting, and assuming his preference is to remain where he is, I'd approach his current manager to say he'd like to discuss terms and conditions, knowing he has an offer in the bag. This makes any negotiation much easier to handle, knowing there's a fall-back to hand. No need to disclose the offer initially. Take it from there. Disclose the fact of the alternative offer existing if you want, depending on how the initial interaction goes, but the danger is it will be seen as a threat to leave (which it is!), so needs phrasing carefully.
No harm in reading up on the following if you haven't already:
http://www.citizensinformation.ie/en/employment/employment_rights_and_conditions/