Poor behaviour of manager and false information / advertising

Have had a shocking experience with Woolworths Canal Walk. Received a voucher for “10% of Lindt Lindor boxes 500g only”. This is the exact wording on the voucher in the app and on the web page (no other terms & conditions). On getting to the till the lady rings it up the 5 boxes that I bought (the only ones on the shelve) and the voucher does not work. She then calls over a supervisor who looks at the voucher and says that there was a mail about it, and they cannot accept the voucher as they were advise no to honor it as it is for boxes that are not sold anymore. Does not apply to what I bought; the boxes were marked Lindor 500g only. I refused to accept, and they call the manager who comes over with an attitude and states clearly only app**** to the red boxes and he cannot override it. Also says that it is a personalize voucher and the stores can decided it they want to accept or not. They have no control over what the rewards department does. He blatantly refuses saying I am wrong, and I must accept what the systems says. I even show him that there are no terms and conditions, but he says he does not care, the system gives a different barcode to what I bought, and I must accept it. He is right and he will never override the system. Socking behavior and attitude! This is blatant false promotional information provided!