Misleading the customer on the proof of payment or they terms and conditions does not correspond with they rules instore

Had a lay buy with them wanted to cancel but they refused but on the til slip or lay buy slip it says u can cancel than they will deduct a 10% of the value of the laybuy When I got there the manager was rude didn't even have time to listen to my complain even ask can I mbe just change it for something else n he plainly refused without listening to me