When you paid your landlord the deposit they have 30 days to protect it and provide you with the prescribed information, if they didnt do this within the timelimit or protect it at all you could pursue for up to 3 times the deposit amount. Check when your deposit was protected with the deposit scheme check the dates, you can search for your deposit on the websites. If its not protected or they messed up you have a strong negotiating position as if the deposit wasnt protected correctly you could take the landlord to Court and claim up to 3 times the deposit amount back. You dont have to go to Court but its pretty black or white if they havent protected your deposit correctly as they know they could be pursued so they might be more willing to simply return your deposit instead.
As a tenant you are responsible for returning the property in a similar condition as to when you first rented it minus fair wear and tear (i.e. minor scuff marks, normally worn carpet etc..). The Deposit Scheme (and Court if legal action is taken) would consider the deposit your money and the onus is on the landlord to prove damages, in order for the landlord to do this they would need to have evidence of the condition of the property at the start of the tenancy and evidence at the end. If they dont have evidence of the condition of the property at the start of the tenancy then it might be difficult to prove what (if any) damages were caused by yourself or if the damages were already present in the property as there is no proof of the original condition the property. Yes they might have pictures of the damages when you moved out but do they have evidence of the condition at the start of the tenancy?
The first step would be to check the deposit protection scheme and make sure your deposit was protected correctly, then you can request before and after pictures of any damages they wish to charge as evidence. If they cant evidence it you can challenge them informally first however if they are still refusing go through the deposit protection scheme.
You only have 90 days from the date your tenancy ended to use the deposit scheme so dont wait too long!
If the landlord has evidence of damages and you accept that you caused them, the landlord can only charge you the reasonable and actual cost to repair the damage. The Tenant Fees Act 2019 banned landlords and agents from charging 99% of fees and this also covers damages in regards to deposit deductions, see pgs 60-61 of the guidance notes here:
https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/922900/Tenant_Fees_Act_-_Tenant_Guidance.pdf The landlord can only charge you to put him back into the position had the damages not occured. For example if you damaged the door and the landlord was charged £200 for a similar replacement, the maximum they can charge would be £200, the landlord should not profit from the damages. If the landlord decides to put a £1000 door on instead then this would be an unreasonable amount and would result in the betterment of the property and so you should not be liable for the full £1000 but you might be responsible for whatever a like for like door would have cost.
I would stress im not legally qualified or anything, not sure how strong the arguments are or if you would be succesful or anything so take it with a massive pinch of salt and seek housing advice from Shelter, Citizens advice etc....
