Ipad Bought Have Mismatch Barcode On The Bill Receipt And The Item

Hi,I bought an IPAD 3 from Walmart, 13201 Ranch Road 620 N, Austin, TX on 03/23/2012. I was looking for an IPAD 3 16GB WIFI and as the model i am looking for is not there in the store at the time i bought, i told them i will for 64GB instead and return it in a week and get the 16 GB one.When i went to return the item on 03/30/2012, i was surprised to see the bar code mismatch. The barcode that came up on the receipt and the barcode present on the item were not matching. They denied me to take the item back and refund me the amount. I even checked with the branch manager who did not help me out. I even checked with the sales person who billed me, but she says i cant help.It looks like they intentionally put the wrong barcode on the receipt to not to have me return the item.I do not really not sure how to proceed. I am even ready to be scrutinized by the video cameras that are present all over the store to prove that i had bought the same item on the date of my receipt.I would really appreciate if you can direct me in the right direction to resolve my issue.The amount of the item is $829 excluding the tax. Please help me.Thanks,Kiran.