When a tenant breaks the shower but denies it?

[NYE2015]

Tenant lived in the property for 18 months with no complaint about the shower. Suddenly reports the shower stopped working, so I sent round a contractor to mend it.

Contractor says the shower looks tampered with and the case is bent out of shape, rendering it unusable. The tenant denies touching it and said it's been like that since he moved in, even though the inventory shows it was fine.

The letting agent says I have 2 choices. One to repair it and try to charge them, or two, to wait until they leave and try to take it out of their deposit.

My past record of deposits is that you don't always get it back, even if it seems incredible that someone would rule in favour of the tenant. In the past I've been 1k out of pocked when a tenant left and they disputed costs from damage they caused.

WWYD?

Do you have pictures of the shower from before the tenant moved in? ie for the inventory etc (my old landlord was very thorough and took pictures of absolutely everything and gave me a month from the date of moving in to add any pictures to the inventory if he'd missed anything).

If you do, and the plumber is correct that the casing is now bent etc, you can prove that it wasn't in that condition prior to them moving in.
If not it's sadly a case of your word against theirs and you will more than likely end up footing the bill for it.