Telkom sales ****

I have made a contract upgrade for a contract of R245, but they are sending me an invoice of R745. I went to the branch and they told me that the consultant who did my upgrade increase the spend limit which is something we did not agreed on. I am not paying this amount. They can even play the recording of that conversation, the consultant at the branch tells me that online sales consultants do that often as they want to push sales.