You could try talking to the Environmental Health department at your local Council (Brighton & Hove,Eastbourne and Hastings). Your landlord or letting agent may also be able to help. If the situation's really bad then Union Support can help explain what options you may have for taking legal action. Most mould, though, is caused by behaviour, rather than structure; are you heating/ventilating the space appropriately? Are you drying clothes on radiators? Is the mould forming behind large items of furniture where no air can circulate? Are you opening windows to ventilate your bathroom from steam when you shower?