UNIPIN SMS VOUCHER NUMBER ISN'T LOADING

I purchased electricity to the total value of R300 from an engen garage as usual. I got one voucher for R200 and another for R100.I had no trouble getting the R200 voucher to load when I punched the sms voucher number onto the meter. But the R100 sms voucher isn't loading. I've been calling and emailing virtually every contact detail on you website to no avail. <br> <br> I'm very frustrated because it's not the first time this has happened.I encountered the same problem in February when one of the vouchers wouldn't load on the meter.<br> <br> The voucher serial number is ***. The slip instructs you to send the voucher serial number to 43471 if you have any queries, but all that gives you is the same sms voucher number that doesn't work in the first place.<br> <br> Don't you have a call centre or at least have someone who actually answers the phone and knows how to help such situations?