Hi perrydavid.. I don't follow when you say transaction stopped.
Its a two step process to purchase an item so difficult to make a mistake. Entering credit card is paying for item not buying.
Two options , pay or ask seller to cancel. Seller doesn't have to. Can open an unpaid dispute and nonpaying places a strike on your account. Two strikes and your buying on eBay is basically ended for 12 months...
http://pages.ebay.ca/help/buy/questions/unpaid-item.html