Neighbour has threatened violence, landlord is not doing anything

long story short, I live in a flat in London and the downstairs neighbour and his girlfriend are extremely volatile (potentially on drugs). Back in February, we called the police on them as they were in a screaming match and it sounded like it would get physical. When the police arrived, we overheard the neighbour telling the officer that we were the problem, claiming we constantly complain about them. The girlfriend turned the police away and a couple hours later, we heard the neighbour scream outside our door, threatening to stab us. We have this on video and made a police statement the next morning. We also installed a security camera outside our door.

We complained to the letting agent (who also manage their flat) after this incident occurred, however, they did not do anything. For context, last year, we were informed by the letting agent that the neighbour had been served an eviction notice and that they were going through the courts to get a bailiff warrant. There has been no movement on this since.

This past week, at 1.30am in the morning, they were fighting again and the girlfriend wrongfully believed we had screamed at them from our window to shut up. She then proceeded to bang on our door and threaten to knock our door down. We are now living in constant fear that something will actually happen to us.

We are due to leave in September. However, given this most recent event, we are now looking for temporary accommodation (out of our own pocket), as the landlord has refused to pay for us to be rehomed elsewhere until the end of our tenancy. We would like to request the refund of our July rent payment as we haven’t been able to return to the flat since this incident. Are there any other options that we should consider in order to put pressure on the letting agent / landlord?