Is the seller allowed to cancel a transaction after I used "buy-it-now" and paid for the item?

[zizzer2000]

I had an item in my watch list for a few days and noticed yesterday that it showed it was having a 50% discount on. I bought it using buy-it-now and paid immediately afterwards. Today the seller emailed saying the 50% discount was a mistake and they want me to paypal the additional money or accept a refund.  Are they allowed to do this?

[ok_so_im_50 · Accepted solution]

Do not pay any additional money. If the seller sends you a transaction cancellation, select the decline option and leave negative feedback.

[heidilynn0_3 · Accepted solution]

Sellers are responsible for their mistakes but can't be forced to complete a transaction.