So, the company sent him there to do work, but his expectations and their promises and the reality didn't match and he wants to come home ?
Apart from the ticketing issue, he needs to talk to the company that sent him there *anyway* and explain why he's leaving and work out what's going to happen when he doesn't turn up for work one morning.
Once that has been addressed then the ticketing issue may be sorted. If the company agree with the basis for his complaint then they may well take care of sorting out the ticket, but if they don't agree and wany him to stay then he may be on his own in terms of the rebooking.
z