(ShareCast News) - Sports Direct has been found guilty by advertising watchdog of making misleading offers for football kits on its website.The Advertising Standards Authority banned the "misleading" advert for an Arsenal FC football kit - and any similar repeats - as it said the FSTE 250 sports retailer has made "unsubstantiated" claims about savings.SportsDirect.com had advertised a £17.99 saving for the Arsenal home shirt in February, but a customer said the product had never been sold on the site at £59.99 and so complained that the price and savings claim were misleading.Sports Direct said the £59.99 claim was based on manufacturer Puma's recommended retail price of the shirt and argued other clubs consistently priced football kit shirts at between £55 and £65.But the ASA disagreed and upheld the claim, considering that consumers were likely to understand that £59.99 represented the price at which the kit was usually sold on Sportsdirect.com, and that the £17.99 saving claim was based on that usual selling price.It warned the company off from making "savings claims that were likely to be understood as being based on the prices at which the products were usually sold".The ASA also told Sports Direct to "ensure that they made clear the basis of savings claims in future advertising, if the savings were intended to be based on other prices that were not the products' usual selling prices".Wider issue?The case mirrors recent findings of the Competition & Markets Authority about supermarket promotional practices, following an investigation and super-complaint by consumer body Which about 'was/now' price offers. Grocers had been criticised for their "confusing and misleading" promotions, with some deals said to have broken trading laws.The CMA said on Wednesday that its main issue was with grocers' use of 'was X/now Y' offers and multi-buy deals, where it questioned whether these were being applied appropriately, with shops moving prices of products up and down in a way.