simcard cancellation

Im very frustrated as i have called Mr Price Mobile to cancel sim that was offered by the store and later on activated telephonically but i have never even inserted that simcard in my phone r used it it is still intact i have been paying for the sim card and not using it. Now that i query this and want to cancel it. Im being told it will be cancelled but it has not been done till i was now informed its 30day process. I want this cancelled with immediate effect. I have called in numerous times but there is no record on their system that i have called and canceled this simcard.