Council changing size

[tootle7]

Can any help as I haven't been able to get through to shelter or citizens advice.
I live in a council property which was let to me as a 2 bedroom, it was advertised and on my tenancy agreement as a 2 bedroom and for housing benefit purposes it's a 2 bedroom but because of an extra wall put up by themselves making an extra box sized room they are saying it's to be classed as a 3 bedroom now. This would meant I'm not entitled to the size of property, I have lived here for 3 years and my tenancy runs out in 2 years which would be the usual point in renewal.
Can anyone advise me on what is likely to happen? As it's not a fault of mine can they still evict me or would they have to wait until my tenancy is up?

They won’t evict you you’ll just be under occupied for housing benefit purposes.

Ok that's fine it's mainly a stable home I'm concerned about. Do you happen to know if when they review the tenancy at the end of my 5 years to see if I still need social housing, if they will evict me then? Or would (if I was still in need) be able to have a renewal whilst still paying the bedroom tax? Its my first social housing home so I'm not familiar with how it all works.