wrong birthday date

I am really unhappy with spur! I received a message from spur for my daughter to come and redeem a birthday voucher which is valid for 3months from the day of her birthday. Her birthday was on the 19th November and we went to spur on the 19th of Feb just a day before it expires. I gave the card to the waiter who checked and told me there is no voucher on the card. When the manager came he told me it expired yesterday on the 18th Feb. According to their records my daughter's birthday is on the 18 November, I tried explaining that is on the 19 november but both the waiter and the manager were not interested in my story. I told them the person who captured the form on the system captured incorrectly as I submitted a hardcopy. The manager was really not helpful or willing to resolve the matter! I had to pay for a meal I did not budget for just because spur made a mistake!