Lord of light... I have no idea how it works over there in yon sceptred isles, but if they're still being a gigantic butts, here's my suggestion.
I. Write a proof of residency.
Samples can be found here, but all it really needs is your location, name, and a signature.
II. Go to your local government head/hall and get it notarised.
III. Present the signed & notarised document to your landlord's company, preferably with ID. If possible make, sure to confirm they received it; this will be helpful if, ten years in the future, they complain about said tenner again.
You're probably already past it, but I hope that helps some.
I'll put extra jasmine in the next cup, for you and yours.