Expired voucher

I would like to complain about boxer super market, i had a voucher that expired during the looting, i called boxer's call center number that appears on my sleep, was told that the voucher will be postponed till end of September, but when i go to the store was told the voucher has expired and there's nothing they can do, im upset because i used my time, airtime 2 call the call center and been send from pillar to post, but still can't redeem the voucher.