Landlord wanting us to replace radiators

Hey everyone, I need some advice…

I recently moved out of a flat I shared with a few people, and, as expected, the landlord is trying to keep as much of our deposit as possible.

Here’s the issue:

Our contract says we’re not allowed to use the radiators to dry clothes. We didn’t realize this rule at first, so we used a spare bedroom in the back to dry clothes. The radiator in that room is completely fine.

However, the radiators in the front corridor (on the ground floor) have rusted at the top. We never used those radiators to dry clothes, as we always dried things in the spare bedroom, which is at the back of the house.

The landlord has a picture from a property visit showing clothes drying in the spare bedroom, and now he’s claiming the rust on the front corridor radiators must be from us drying clothes there. But again, we never dried anything near those front radiators.

Am I liable for replacing the two radiators in the front corridor that have rust at the top? As I mentioned, in the three years we lived there, we never used those radiators for drying clothes, and there’s proof that we only used the back room.

Any advice?