I'm not sure what you're looking for? Are you looking for a rent reduction to compensate for the things wrong with the house, or do you want the agent to come out and be in the house when maintenance is being done?
If it's simply that youre trying to get work done quicker, then you can do as Law Student says and give a deadline then get quotes for the work yourself, but this will take more of your time.
In reality, if the house isn't suitable for whatever reason, or youre unhappy with the way the agent works, then it may be better to simply move. You say you don't have the time, but how much time are you spending with maintenance people at present? You can leave without notice at the end of the initial 6 month term, though its polite to give notice, or by giving 1 months notice whilst on the periodic tenancy.