Bash is a BALDERDASH!!!!!

I ordered a pair of sneakers at a 30% discounted price. When the order arrived,it was incorrect as they sent two left foot shoes. I logged a return online and contacted their customer care and was advised they will rectify the matter only for them to send me a voucher of 25% instead. The mistake was on their side and yet they can't even rectify the error and give me the full discount.