Dear tecniq,
Some times it happens (regarding case 1). Try convicing your buyer that the datacable is not included in the product as per the description.
I suggest that solving the matter with buyer is better than going to third party.
On Case 2, If the buyer has not responded to your Dispute, then eBay will remove the feedback. But in your case, I feel he has been responded to the UPI Dispute. But here you are lucky as the you both have agreed for mutual withdraw.
I suggest you to leave neutral feedbacks for the buyers who don't make the payment. This will be a safe play till a level.
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With Regards,
Navaneeth (snrama)
😉
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With Regards,
Navaneeth (snrama)
😉