i'm with you 100%. it has nothing to do with the dollar value, if its $6 or $600, i would feel the same way.
i can not believe he didn't refund the money to you. thats very short sighted and if it were me i would never shop there again.
i had a problem with an online fabric store regarding shipping, they sent me an email stating that they charge only the exact shipping amount and when i got my package they overcharged me on shipping.
they wouldn't correct the mistake since it was such a small amount ($2) and i stated that the amount shouldn't matter - its your written policy and should be honored to all customers.
needless to say, i contact the credit card company and provided them with the email and my receipt, the credit card company reversed the entire charge from the online store.