Flipkart — Oppo Enco Buds Low range

My oppo enco buds disconnects frequently and it already had black dust particles at the time of arrival also had a big scratch near the charging port when it had arrived.
The technician gave a visit and he saw the same issue but still rejected the request and said "thoda 19-20 chalta hai"
The charging in both buds is never same and always of a difference of 20-40% inspite of charging.
All these issues i want to return the product and not at all satisfied with the Flipkart customer support as they always abuse over the call and hang up.
on my app there is a return button but it never works.
Order I'd : OD[protected]
Invoice no : # FAJ4YY[protected]