Castle Water Reviews

My mother owns her home and outside her back gate is a drain. The drain is situated in an off road set of garages. Apparently the drain is on my mothers house plans and belongs to the house? Since 1974 when the house was purchased she has paid a yearly charge to Thames Water for the sewerage. The cost has ranged from £2 a year to this years bill showing just over £20. Each year the bill has read 'Unmeasured sewerage RV' Never before has it shown a charge for 'Unmeasured sewerage Fixed'. Having phoned them, they said that the mistake was their fault in that they had omitted to charge for the last 2 years, but that they were not going to make my mother pay for their mistake. This has caused my mother who is 89 make herself ill over it. Has anyone else had this happen to them? Is this legal? Any advise would be great.

They have been chasing me for £3K for 5 years which I do not agree with but they won’t listen to reason. Has anyone had success with a solicitor or lawyer who knows how to tackle them ? Any recommendations please…