OnePlus India — About generating the coupon

My one plus buds z product defective and the product is in warranty period so I can send the product to service center from 1 and half month but they didnt do anything ..they call me and told mi that white earbud not available in stock ..so they generate a coupon instead of one plus bud z then i call 4 to 5 times to the one plus toll free number that generate a coupon as early as possible then they forward a complaint to the escalation team and they said your coupon will be generated in 24 hour but no coupon generated in my mail I'd ...it's 1.5month so please my compaint will be solved in as early as possible