I suggest that you make a claim in the small claims court for the amount charged, which I suppose has been taken from your deposit.  You will have to pay a fee for doing that but the amount can be included in the claim you make.  I doubt the landlord will take the trouble to go to court for £150 so may pay up but you should be aware that I have seen cases in which even awards made by a court have not been paid and then it can be a long stressful and costly business getting what is due.  It may be better to write it off to experience.  Much depends on your tenacity and ability to stay the course.

Glad to have found thid website especially because I'm a Canadian letting in the UK so I'm not familiar with UK legislation regarding landlords and tenants. What happened was that the sliding shower screen door in the bathroom was occassionally tough to close but not so much that I thought it warranted immediate attention. One day I could not for the life of me get it unstuck and the whole door fell on me in the bathtub, I injured myself though not seriously, and it made a small hole in the tub. I immediately called the letting agency and told them what happened and they sent out the contractor, who by the way is a close friend of the landlords, came in and siliconed the hole and a few days later replaced the door. The door did not brake it was made of probably plexi-glass, the letting agency said they would let us know who was to pay for it. We kept asking thinking it was a poor quality and faulty door that was installed in the first place and for three months we could not get an answer. Finally they said it was our fault and responsibilty and said they wanted 180 pounds for it! To this day I have not seen the invoice and considering the close friend of the landlords installed it I positive it could not have cost that much. They have been very rude when before this we had a great relationship and dismissed me saying the price was fair without showing me the invoice! I think the burden falls on the landlords but don't know how to prove it! If anyone can help that would be great!