Blue Star India — Billing amount

My Blue star water purifier had a problem.A ticket was raised by me.
Technican repaired and charged me amount pertaining to 3900 rupees.which i have paid him through Phonepe.Still the issue was not solved.i called the Service desk again and raised the concern, they told they will send a technician to complete the work but no one arrived and issue persists.i received a mail today that the work has been completed and charged amount Zero.

What is happening here.The issue is not resolved and they took my money.
i want my money back or else i will raise a Customer Court Ticket soon.(core.nic.in)