[Celyn]

I've not been in that situation, so probably can't really advise on how to deal with that (aside from saying it's a good idea to keep on avoiding them). But I wanted to say that it's not your fault, for the way these people are behaving towards you. And yes, I would call catching the manager making faces at you behind your back bullying- it's childish, unprofessional and totally uncalled for.

Unfortunately, some people will find it difficult to get on with you for whatever reasons they have (even the possibility of a personality clash is one way of looking at it), but it doesn't mean they should result to bullying you. They are at fault here, not you.