Batteries and complaint

I bought a Smoking Anywhere starter kit at a mall in Tyler, TX. The guy charged me double the cost of online purchase. He even went to his computer and said "Let me see if I can get you an online special." to make me think I was getting a good deal. He charged me $135.00 for a starter kit that is $79.00 online at your site. As well the batteries , once charged, last about an hour. I do not have the sales slip but I do show the purchase on my bank statement. Can I use it to get a refund or at least replacement to see if replacement parts work better. The atomizer worked for about a week. Please advise.
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Obviously you can get the refund if the transaction statement is there with you...