No service from Vodacom

I've got a problem with Vodacom. I upgraded online on 24 March 2019 and chose my new package and new phone at R749 for 24 months ( I've got screenshots bro prove this and sent it to them) when I received my upgrade confirmation it said 36 months at R749. I have been trying to sort this out with Vodacom since 30 March. I've spoken to various consultants, all with different excuses. One said that there was a problem with the app that's why it showed 24 months, another one said that they thought it was just a printing error and if it wasn't corrected by 1 May he would get back to me ( he never did) every other time I've been told that the online department would contact me, they never have. I've written on their Facebook page various times and just get the standard reply that someone will get back to me, sometimes they phone and tell me they will get back to me but no one ever does. I really don't see why I must pay an extra 12 months for their mistake. They have now also added on to my account payment for the new phone as well as my old phone, that I was also never told of and don't understand why this is happening. I eventually got a reference number from Vodacom it is: 1- ********** **********