Rejected voucher

I ordered a item and wanted to use a R200 voucher but the voucher number was rejected as code not valid! I send them a e-mail and got back a automated response that they will come back to me, that was on 7 January 2022. I phoned them the next day and they also said they will com back, still no reply and the voucher did expired today. What now? What a pathetic company!