If you're facing an issue while renting a flat, the first step is to contact your landlord or letting agent directly to raise your concerns. If they do not resolve the matter, you can escalate the complaint to a relevant trade body, such as the National Landlords Association or the Residential Landlords Association, depending on your landlord's affiliation. For serious issues, especially regarding health and safety, you may also contact your local council's environmental health department. Keep records of all communications for reference. If the problem still isn't addressed, seeking advice from a housing charity or a solicitor can help guide you on further action.