How to answer this Land Law question on tenency??? help plz!?

Ernest is a student who is the tenant of one of several flats in a large house owned by Rachel. In common with the other tenants Ernest signed a three year lease which contained a covenant by the tenant to use the premises for residential purposes only. An adjoining flat is occupied by Moll, a prostitute who disturbs Ernest by the rowdy behaviour of herself and her clients whilst he is trying to study. Moll’s behaviour is ignored by Rachel since she pays twice as much rent as the other tenants. Rachel has also installed a new central heating system which does not work properly. Ernest has no hot water supply and the heating works very sporadically. There is also damp in Ernest’s flat. Ernest wishes to inform Rachel that does not intend to pay his rent until the defects are put right and something is done about Moll’s behaviour. Advise Ernest.