Poor service

I got a voucher for R500 and place an order for R222.90 so now I want to use the balance but it says error. Please advise how will I be able to use the balance the voucher number was NKB3467BA80 Order Number: DFD***9 mow instead of them finding a solution they taking me to pillar to post .Can they please advise how am I going to get access of my outstanding balance.