As would have been clearly outlined in the description of your package upon purchase (see below), this pass option allows holders to spread the cost of their yearly subscription across the year in 12 monthly instalments as opposed to one large upfront payment (as with the regular Annual Pass subscription).
When you signed up to the pass you signed up to a 12 month contract with us. The pass is not a pay-per-month pass that you can simply cancel at any time and payments will cease.
You can set your subscription to cancel at the end of the subscription period under the MYGAAGO section on our website when logged into your account but payments will not cease until all 12 payments have been collected.