Rent Arrears and Damage by tenant

Tenancy Types and Management

We rent a three bed house to a woman and her three sons (baby is a few weeks old). The agreement is with her, but her boyfriend has moved in since the baby has been born. A few problems:

1) The tenant is continually late with her rent, it eventually gets paid when I contant her guarantor. Means lots of additional work for me. I have served a section 21 which has expired so can go to court for an eviction. Seems the best course of action to me, but does anyone have any oither suggestions? I am worried she can use the new baby to delay any eviction.

2) On New Years Day (3.00am!), the tenant's boyfriend kicked the front door in as the lock had apparrently stuck. The door and the lock were 9 months old and had been fitted by a good joiner. The tenant hadn't reported any problems with the lock to us although she said that it had been a problem once we saw the ruined door. The replacement was 450 + vat inc labour as it is an oversized door. It is my opinion the tenant is responsible for this cost and shoud repay us for the work. She hadn't paid it and will no doublt say it is our respnsibility due to the alledged problem with the lock. Can I pursue this? Considering small claims court

Thanks for any advice.