You don't need any help from eBay.
It's open to your seller to cancel the sale, and refund you. If they don't want to do that it's probably because eBay penalises sellers who make seller-initiated cancellations which may just be an excuse to avoid selling, such as discovering a fault with the item.
If the seller doesn't refund you, and you don't receive your item, wait until the latest estimated deliver date has passed and then open an "item not received" case 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/
Be sure to read and follow the instructions correctly.
