Southern Water overcharging

Hi everyone and a happy healthy new year to you all

My son lives in a one bedroom flat, he is a builder who leaves home approx 7 am and gets home anywhere between 6 and 7 every evening maybe a little earlier in the winter.

Since 2016 when he moved into the flat the water bills have been really high Southern Water agreeing to this came out and discovered that he was being charged on a meter but there was no meter for his flat. They stopped taking money from him for the best part of a year as they worked out how much he should have been using.

They then put in a meter although the first person who come out
to install one said they couldn't put one in place as the plastic piping that was used to supply the water had overtime proven to break down by cracking. The second time approx a year later one was put in as the bills hadn't dropped when he complained again.

Has the overcharging stopped NO IT HASN'T and when on the phone to Southern Water yet again they agreed he couldn't be using that much water and was asked if he was using it to fill a swimming pool.....WHAT he said before bursting out laughing.

We have yet again been asked to do a tap test which was done yesterday and the meter did not move so there is no way there is a leak from the meter to the flat that makes us think they are ignoring the meter reading and overcharging automatically.

Has anyone got any ideas what could be happening this has been going on since 2016.