I am so confused as to how this works

I have a contract for 2 tablets with Vodacom, in May 2016 I was contacted by an agent stating that I was due for an upgrade which I did. When my debit order went through at the end of the month I had to pay for 4 contracts, when I queried it I was told it was because I had upgraded to early NO amout of complaints helped then, I paid 5 months for the other 2 tablets. Now I get told I can only cancel my contract in August as I am still on the old contract. According to Vodacom the old contract NEVER expired?