Old Mutual Unfortunate

Last month old mutual deducted money from my account so I reversed the debit order the bank asked why and I chose the option not authorized because I never took my car to a auto boys shop for inspection. With no inspection they can't help with insurance. Last night they deducted another payment but no they put a block on Nedbank side so I cannot reverse the payment also I phoned Old Mutual and the assist said no they do not pay you back even if it is less than 24hrs. I am in deep very deep **** because of this. How can they put a block on Nedbank?