Does a pasta source contain pasta?

Latest batch of vouchers I got for my Tesco loyalty card included one for 40p off Tesco chilled pasta sauces.  So I turned up at the checkout with a tub of sauce and presented the voucher.  The assistant scanned both and the voucher wasn't accepted.  She looked at the tub and said it was not a pasta sauce, it was a beef sauce.  (Fully, it was beef bolognese sauce.)  OK, she was of Chinese or similar ancestry, but she was working in a supermarket.  (And isn't there a story that Marco Polo brought pasta back to Italy from China?)  Another assistant came to the same conclusion, and mis-read the voucher as saying "chilli pasta sauce".  Finally, their team leader was called and he told them to override the scanner.