Voucher ****?

Not sure if it's a **** from Jet or poor Jet system or inadequate training. I got an SMS from Jet stating that all thank you cards are being discontinued and I'm given R250 voucher for last usage and the voucher number is written. I went to Jet the Groove Mall with the sms I asked one of the Jet personnel if it is valid before picking clothes; she said yes but when I got to the till I was told the voucher number can not be used, I need to wait for another sms that will give me another voucher number stating with zero's. I went back home waited for that sms and I haven't received; it's been more than a month. Today I went to Jet Silver Mall, I also started by showing one of the Jet Personnels and asked if I can be able to use the voucher; she said yes, after picking I went to the same person to pay, all of a sudden she couldn't assist me because I've forwarded the message from my other phone that had a problem to the one I was carrying. I was surprised cause I had my thank you card, ID document and the voucher number and it shows it's from the initial phone. unfortunately the other phone is broken and had to save and wipe all data before sending it in for repairs. I just feel like there's so many stories with this vouchers and I looks like it's a trick to get people to buy because after picking you may be tempted to pay to save yourself from an embarrassment. :-(