Double debits 2 months running!

My name is Adrian Adams and I have purchased a Corsa Bakkie through Wesbank in 2012, for this year alone I have been double deducted for my installment of R2193.44 per month and then have to sort out Returned payment penalty's with my bank out of my pocket yet they are making the errors! there was an arrangement made for a double deduction which shortly there after I cancelled with Wesbank on 2 different occasions yet get told their system shows no cancellation on my profile. Why should ,I the client foot the extra bills for people who are clearly *********** and cannot provide the service they promise to lure clients with? If i didn't have to pay for 2 more years on this vehicle surely I would have given them the middle finger immediately due to the stress they have caused me and still are causing!