It may well be a legal obligation. Sorry, as I know it's not something you want to hear.
www.gov.uk/government/publications/landlord-and-tenant-rights-and-responsibilities-in-the-private-rented-sector/landlord-and-tenant-rights-and-responsibilities-in-the-private-rented-sector
"There are 2 types of hazards – category 1, which are the most serious, and category 2. Examples of category 1 hazards include:
exposed wiring
a dangerous or broken boiler
rats, pests or other infestations
damp and mould on the walls or ceiling
Health and safety risks in the home are assessed by local councils using the Housing Health and Safety Rating System (HHSRS). There are also additional health and safety requirements for housing in multiple occupation (HMO). HMOs are shared homes containing multiple households such as bedsits, shared student housing and hostels.
Reporting a hazard
If you’re worried about a potential hazard in your home, you should report it to your landlord or letting agent immediately.
Once you’ve informed them about a problem in the property, your landlord is responsible for most repairs. However, you should give them a reasonable amount of time to carry out the work.
If you’ve reported a potential health and safety hazard and your landlord or letting agent hasn’t resolved it in a reasonable time, you should contact your local council. An environmental health officer may then arrange to visit your home to assess any hazards within it. You can also ask the council to inspect a neighbouring property if issues with it could affect your own health and safety.
Enforcement
The council must take action if it finds any category 1 hazards in your home. For example, it can order your landlord to carry out repairs or make improvements – and if your landlord or letting agent fails to do this they could be prosecuted and fined. The council can also take emergency remedial action if it thinks you are at serious risk of harm. In such cases, the council has the right to carry out the necessary work and charge your landlord for it."