My mum's been overcharged on her council tax and one reason seems to be that the council believe that I'm a resident at her house and that I'm not a student.

In fact I live elsewhere most of the year and am a full time student.

Now we have two possible arguments to apply for a refund:
a) I'm a student
b) I don't live there

I got a certificate of student status from the university and sent it to the council but they're are being too banal about what they accept as evidence so b) seems an easier argument.

The only problem is that I do in fact live there over most of the summer and for a few weeks spread over the rest of the year. So what does resident mean? If I live there for a few months a year am I a resident?