Hi, she has to get his written permission to change his surname as my friend just had my goddaughters surname changed as her father isn't interested in her-he still had to sign saying he gave permission.
As for the holiday-its a shame but I think she can do pretty much what she wants there-unless they have a written agreement to state otherwise. Have had the same sort of problems with my partners ex and its just a real shame that some people are so spiteful their children have to suffer because of it!
Maybe you or your son can find a few answers on this site
http://www.fnf.org.uk/law/rgind.htm
we found it helpful, the only thing I can suggest in the future is that he gets to know his rights and asserts them.
I hope this helps!
:O)