AO Smith — I am complaining ro service technician

Dear Sir I raised a complain about my water ro .one technician visited and told us that membrane has been blocked.and he said amount would be 3200.so we decided to do afterward but he asked for visit charge we paid him 400.but today I got a bill from ao smith and in bill it is mention that we received 0 zero rs from us.case no 17759239.pls look into this issue.