********** upgrade processed

i have a contract with vodacom that was due to have been completed in march 2015. it usually goes on to a month to month basis. i now decide to have it cancelled and been told the upgrade has already been processed during january 2015. how is this even allowed to happen if i have never been to the store that supposedly upgraded the contract and investigations can take time as i am told so i must continue paying the contract whilst vodacom sorts out the mess