Water Bill caused by incorrect initial reading

Polaris49

My boyfriend has just received a bill for £1300 for water in his flat he moved out of , and started renting out in February. I suspect it has been caused by an incorrect initial meter reading. Is there anything he can do? It’s a 1 bedroom flat and he had been paying £28 per month for the first few months which was then reduced to £20pm after the first 6m by southern water (so obviously no sign anything was amiss). He closed the account in February and all was well. He then got this bill through. They claim they took the initial meter reading but is there any way to get them to investigate this? 

£1300 in a year for one person in a one bedroom flat is impossible! Help! 

pochase

What reading did he give when he moved in? Is that reading shown on the bill?

If there is leakage at all, even something small like the cistern of your loo running  a small amount, it can easily add up to the £1300.

Cardew

When he 'closed the account' did he give a meter reading?

Were his previous bills based on estimated readings?

What he paid by Direct Debit is only relevant if it was calculated on actual(not estimated) meter readings. However if Southern water reduced his DD from £28 to £20 after 6 months one must assume that was based on actual readings. How long was he in the flat after the DD was reduced?