Unable to change to 79c prepaid option

Hi, I am still unable to change my plan to the 79c option . I have tried the following: *111# and following all USSD options until it says "confirmation sms will be sent" but no sms ever arrives. I have dialed 1181 and followed all options. voice prompt tells me I have changed to 79c plan but whenever I follow up it still tells me I am on the bonuspower plan. I have gone on to the vodacom web site, logged in changed my plan there. Again it tells me that the plan has changed but when I check again next day it has either reverted back to power plan or not changed it. I has been over a week now and still I am not able to take advantage of the 79c call plan as advertised.