The only way to guarantee a refund is to use the ebay guarantee.
You open a return case and wait for the seller to send you a prepaid label, you don't pay for the return yourself.
The tracking is automatically loaded into the case details ans once it shows delivered you get your refund.
As you didn't follow procedure and sent the item back yourself ebay will not know it has been returned.
Can you add the tracking number to the case now? And if it shows delivered yo escalate your case if your seller has not refunded within 2 full days.
Unfortunately there is no way to force the seller to reimburse you the postage money.
******************************************************************************************
Powered by cats