Boult Audio — Service center did not give back my product.

My bluetooth earphone boult audio airbass combuds which i order from myntra and due to no return policy i claimed warrenty and send to customer service through shiprocket and after 1 week they send me mail that they got my product and the product will be repaired and dispatched within 3 to 4 working days. It been a month since it was sent. When I send a mail asking for the status, every time I receive the same mail saying that they got my product and the product will be repaired and dispatched within 3 to 4 working days.

what can i do