Childrens birthday vouchers

I feel my kids lost out on their birthday vouchers as we took them to Spur for their birthday and when we wanted to pay the wi-fi was off so we couldn't redeem the vouchers. When we wanted to use it a couple of months later I was informed it expired. If I knew it would expire so quickly I would have used it sooner but as times is tough we don't go to Spur very often only on special occasions. I would like to hear Spur's response to my complaint.