My once off 20GB on contract upgrade wasnot allocated

I upgraded my phone contract in the week uchoose R230 airtime plan like my previous plan. My phone was delivered by Ram on Wednesday 20 May. I received an sms yesterday 22 May to say that my contract upgrade has been completed but when I checked my Vodacom App it did not reflect the 20GB once off Data. It was about 6GB that was added. I would like to know why I did not get the once off data 20GB as it said so on the advert. Is it only going to be added later. YOUR URGENT attention would be much appreciated