Poor service

Went to bp in alrode where they have a so calles promotion where by u buy 2 nestle milky bars and u get a flings or cheese curls so i asked for my free pack of flings i was rold very rudely that they dont have i asked for a refund and was laughed at by the cashier nellie, my money was throw on the counter at me.i have never been treated this badly before and am disguised