I have create Add to cart buttons to my profile, but when a buyer clicks Add to cart and does not realise they have already added this they now have two or more of the same item. Yes they could just reduce the total to one, but what of those that don't realise this and pay more than they wish to, this causes more problems as I then have to refund part of the transaction for their mistake; more work for me.
How do I limit the the cart to only have one of each item they add. Or is there another secure button method I can use ?
It has to be a secure button that can not be altered.
TIA
