Upgrade device confusion.

I am so confused. Being a loyal Customer. I received a call stating that I can come in to upgrade. The MTN Shop at Castle Gate indicated that I can upgrade if I pay in R4000. I left the store as this was very expensive. One day later I received a call from MTN stating that I can upgrade online. Again received a message that I can only upgrade on the 14th of August. Really this is so inconsistent. If I do not upgrade I am going to cancel my contract and go over to another network. Please help me so that I can upgrade.