Unauthorized Debit Order

This company keeps calling me to sell me only God knows what, because when ever they call i tell them i am not interested or just purely hangup the phone as soon as they say who they are. The last encounter, i put my volume in the car on full blast just because they really starting to irritate me now... Low and behold, i receive an SMS informing me that a debit order has been placed on my account. I have no idea how they received my details in order to place an Unauthorized Debit order. All i know is that this company is very shady with their marketing tactics and i refuse to be impacted negatively due to the negligence of their *****ed staff now that i have to have stop orders placed and waste my precious airtime to get them to delete all my details.