barcodes on items in the store

I went to clicks earlier today to buy Facecloth. And the special was buy three and pay for two, so get the third one free. Over excitement as I only wanted two, I then went on to buying 6. Firstly I was in a queue to pay for the items, and got to the cashier she scanned the first three which where the guest towel, then the 3 face cloths, one didn't have a barcode. So she told me that one doesn't have a barcode. For me to go around the tills to get the barcoded face cloth seemed far, as she could have taken at least -5 steps from the cashier machine and get me the face cloth, she refused and told me that she can't leave her till unattended. Hello, you can take just a few steps and get me the face cloths and she decides to put the face cloth that doesn't have the barcode aside and give me my parcels. As it didn't make sense to me to walk all the way back to get a barcoded face cloth. I left the store angry and feeling disrespected as a customer. Whose responsibilty is it, for the items in the store to have barcodes? If it was an item far from her till maybe I would understand, so now I paid for two but didn't get my third face cloth because it didn't have a barcode to scan???