Anglian Water 10 year overcharge?

Good morning,

Please can I have some advice/guidance with regard to a situation I have with Anglian Water?

I recently received a letter from Anglian Water alerting me to the fact that my water usage had increased and my monthly direct debit bill was to be increased from £85 to £142/month.

My next action was to discuss this with AW who advised me that, as the water meter chamber was dry, the issue was mine between the meter itself and my house stopcock and to discuss this with my insurance company. After some further investigations the fault was identified as the meter itself which had a fibreglass exterior that had split resulting in water leaking out of one side & Anglian Water have speedily replaced the meter + housing plus have completed suitable reinstatement works.

This episode has alerted me to the fact that, as a household of 2 (with children visiting periodically) we have been paying excessive water bills from as far back as 2009 when I purchased the new-build property – perhaps the meter has been leaking for a decade. My monthly bills, on average across the years, work out at £57/month when, based on the Anglian Water usage calculator our bills should be circa £38/month (based on generously estimating our usage + 2019 rates & prices).

The response from Anglian Water has been to offer me £910 as a leakage allowance which I have politely rejected and we are going through an exercise to monitor usage over the next 7 days for them to gauge our real usage (yesterday they replaced the meter without any warning or explanation – perhaps this is standard practice.) Their offer was based on their assertion that readings suggest the leak happened around 2017 whereas I have pushed back saying bills have been too high for many years so the leak could have been from 2009.

Is it unreasonable for my settlement figure expectations to be well in excess of their offer? I don’t think it’s unfair of me to expect some form of compensation to cover the inconvenience of being overcharged plus an element to cover interest. For just the water overcharge itself the number feels like it should be circa £2.5k.
For the record Anglian Water have been very friendly & helpful to date however it feels like their motivation is to limit their liability.

Please can you advise/help?

Thank you