Hi there. Your contract is with the l/lord, not the agency. Focus your effort on the l/lord. Read the following thread:
http://www.consumeractiongroup.co.uk...tml#post641938
There is also a lot of info on this forum with regards to disrepairs so I am afraid you have to do some reading.
Start gathering evidence; remember,
strong evidence and facts are unbeatable. Get statements from witnesses, take photos, get Environmental Health officer in, get an opinion from
accredited electrician, plumber.
Decide; have you done enough negotiation to take it further, i.e. reduce rent or fix the problem and use your rent in lieu or go to court.
If you do not feel confident to do it by yourself, see if you can qualify for legal aid:
Legal Aid Calculator
Keep us posted and good luck!