Dear @Pathvandana
For the complaints regarding your airpod, you can first, again visit the nearest apple authorized service center with your previous repair bill. You can also book an appointment for a service request by submitting an online appointment form at apple’s official support website.
Additionally, you can submit an onlinecomplaint form for the technical support.
To know, all the available options where you can complain, please read: Where to file an Apple device complaint?
In case of India, if your problem still persist, you may escalate the case to Grievance Officer of Apple.
Further, you can contact the National Consumer Helpline (NCH) for an informal consumer complaint against Apple.
If you still need help, reply it.