He is in y3 and will be 8 in the summer.
He is being teased by one particular girl who is in his work group so sits on the same table. It's low level mean-ness from the sounds of it, making fun of him not being able to answer a question, his hair, her most recent addition to the insults is that he's 'sooo gay' (and I know the school have been doing a lot recently about using homophobic language). This week she's been sniping at him for not inviting her to his birthday treat 
I have spoken to DS's teacher and she has 'had a word' several times with the girl. The girl seems to quieten down after this and then it ramps up again.
I've been giving DS chance to talk about it, have been giving him plenty of hugs, advised him to ignore where possible and tell the teacher if it gets bad.
Is there anything else I can do about this or does he just have to put up with it? Any advice would be welcome, it's making him
, and me too.