The fact of a stop payment does not erase the obligation for which the check was tendered. At a minimum, the drawer of the check must return the merchandise (if applicable). If it's a service that was received, the drawer of the check and the provider of the service have to settle the transaction. The merchant is entitled to payment.
The bank, if it dishonored the check in conformance to the drawer's instructions, is out of the picture here, and should keep out of it to avoid any liability.
John S. Burnett
Fighting for Compliance since 1976
Bankers' Threads User #8