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Hi thank you for your message, this is a very difficult situation as you will have realised, in essence your options really are end the tenancy but you do not want to do that, use the terms of the tenancy as you have tried to do or ordinarily you could report the matter to the council such as environmental health but in the circumstances as it is rented you would be the responsible party. In the circumstances, however, I consider you would be within your rights to enter and clean up the property not least because in its current condition, it represents both a health and a large fire risk. Indeed, you could be fined or prosecution by the local fire authority for breaching fire safety by the flat being in such a condition. I hope this helps, if you can please accept my answer and rate me 5 stars (in the top right of your screen) then Just Answer will credit me for helping you today.