Sign up for 24 months and now I get 32 months!!!!

Hi. I took out a contract on the 1 March 2015. I received an early upgrade. I specifically asked the sales person if the new contract will only be effective for 24 months, as I knew I might most probably move to another country in 2016 and then there would only be about 14 months left of my contract and then I would just buy myself out. When I wanted to cancel my contract they told me that my contract only expires in October 2017 which means I took out a contract for 32 months!!! The reason I SPECIFICALLY asked the sales person was because I didn't want to have a 32 months contract at the much higher price than my previous contract!!!! What can I do to resolve this as I NEVER wanted to sign up for a 32 months contract and I made it clear to the sales person and he did assure me that it will not be the case!!!! Also the final quote that I received from the branch didn't have any consultant number or name on the form so I cannot tell you who was the person who helped me.