We are having a problem with a bidder using a different ID to avoid our blocked bidders list. Ebay unable or unwilling to assist

[gkam2]

A buyer sent an echeque which bounced, their second echeque cleared on the Thursday before Good Friday. We were away over Easter and this info was displayed on all our listings. Our products are perishable and we only mail on Mondays to ensure that the goods arrive interstate before the weekend. The buyer was advised that their order would be shipped on the first working Monday (not Easter Monday) but on the Thursday after Easter they filed an Item Not Received claim and reversed the paypal payment.. After some discussion the payment was re-instated and the goods were shipped on the following Monday. We don't need the hassle so added the buyer to our blocked list, they are now using another ID to buy again and avoid the blocked list and have paid money into Paypal. We have refunded the payment and requested a sale cancellation which was refused. I would like to know how to resolve this situation and would appreciate your suggestions. Ebay has promised to reverse any negative feedback that we may receive as a result of this. Thanks to all.