Air India — Not getting my refund

Its around 3 month now, i am requesting for my refund but not getting it.Tired of calling air india customer care, they always use to say that your refund is in process and our refund team will contact you but no msg or mail from their side is available, they use to give email id and says please mail all the information on this but those I'd are not working.Mail has not been send on those I'd.
Case I'd number[protected]
PNR number-H86XR
E-ticket number[protected]
Flight date-19 April 2021
Flight from-Delhi india to Heathrow-London, England UK.