Vodacom now wont upgrade at month13

We called in to the Vodacom call centre as we were advised that we could do a premature upgrade from month 13. I was advised we would be able to do this but unfortunately the manager was not in on a weekend to authorize it. I then called in today and was told they will not be doing this for me now and said they just dont do it. My Wife and I spend well over R4500 a month and were told if our spend was high enough that I could receive an early upgrade, Im now told that this not possible. please can someone clarify this as I urgently need to do an upgrade.