AO Smith — AO Smith Z2+ - Faulty and no respite after continued complaints

My Z2+ started leaking water a few weeks ago. After raising the complaint (first raised on 21 May, request#14412345, request#[protected], the service technician has come thrice to no avail. He has overcharged me by asking me to pay to his personal Google Pay account. The problem with the filter has escalated with a shrill alarm coming every time I switch in on (in addition to the leakage). He now suggests we change the display as well but is clueless to the real problem. It has been 4 days since I raised the complaint last without anyone coming to help/fix.

Can you please help with this? I have been writing to the customer care and keep getting empty promises of someone coming to help.