It doesn't sound like a scam to me - more like an inexperienced new or returning seller who didn't realise that eBay would hold your payment as a security precaution for up to 30 days before releasing it to the seller.
In any case, you can't cancel the sale - only the seller can. If you feel charitable you could send them a cancellation request, this would enable them to cancel the sale through eBay with no penalty to themselves. eBay would issue your refund, which would be returned to the source of funding you used to pay PayPal. It can take anything from a few days to up to a month to reach your account. Your thoughtless seller doesn't want to wait for his own payment, but hasn't considered that you may now have to wait just as long to get your money back.
Otherwise, unless the seller cancels and refunds you in the meantime you can wait until after the latest estimated delivery date has passed. You can then open a case for a refund under eBay's money back guarantee. There is a link to it in every qualifying listing, or see: https://pages.ebay.co.uk/ebay-money-back-guarantee/
It's all very simple and you don't need to negotiate with seller. Just open a case and wait three working days for the seller to respond. After this, the option will appear to escalate the case if necessary for eBay to step in to enforce a refund.
A case MUST opened within 30 days of the latest estimated delivery date. Be sure to read and follow the procedure carefully. Don't under any circumstances be talked into closing the case before you have your refund. If there's anything you're not sure about people here are always willing to help.
