Hi Hector: please have a look at the following post
http://www.consumeractiongroup.co.uk...tml#post641938
The disrepairs issue has been discussed here frequently so you need to do some research but when it comes to timeframe then I am not aware of any specific rules that would regulate this. I would presume that the the timeframe needs to be "reasonable" or "fair" i.e. not unduly short or long. It would also depend on circumstances; for example live wires hanging from the ceiling would warrant an emergency, fact response whilst a broken central heating in a summer would not.
Contact your local Environmental Health office- their report would have a lot of clout.
Start gathering evidence; photos, accredited professionals estimates/reports.
Write a short, businesslike letter requesting firm dates for repair and response within a week or fortnight (depending how cheesed off you are

)