My latest bill from Thames water arrived on April ...

My latest bill from Thames water arrived on April 23rd 2020. It was an estimated reading of 1287. I knew that was too high as we had been in Australia for 5 weeks. After taking my own reading of 1264 i rang them and gave them that figure. A revised bill was promised and it duly arrived. This was exactly the same as the first bill. Rang them again on the 28th and spoke to another person, explained everything again. She gave me her first name and a Ref No. 6312664.She even asked me how i would rate the service i had received out of 5. I replied saying you will have to wait until i get another revised bill. This arrived on May 4th with an even higher bill at 1290. Are these people just plain incompetent or don't give a toss. The only way to get them to listen is to cancel my direct debit.