Hello Shona,
I wonder why this only happens in French? Do you think it's because the teacher isn't keeping control of the class?
The bullies are doing this because they know you don't like it. They're trying to get a reaction from you so the best way to deal with that is not to give them the satisfaction of seeing you upset and walking out, Turning a deaf ear at the time is the best idea but then keep a diary at home and make a note of what happened.
Go to see your head of year and explain what happened in the lesson and that the teacher also heard and saw it so that your head of year can do something about it.
I can understand why you get upset and shout at the teacher but she is a person too and she might be having a hard time in the class. If she's having trouble controlling the class then she probably feels very stressed herself.
If you try not to react (and I know it's hard) then that should also reduce the stress on the teacher as you won't be shouting and if you're not shouting then she won't need to put you on report. In fact, the only ones with bad behaviour will be the bullies so it will be easier for her to confirm to your head of year that they are the ones causing the trouble.
Do you see what I mean?
Take care,
Liz
Bullying UK
www.bullying.co.uk