Unauthorised debit order!

Around October/November 2017 i went on their site to apply for a loan but never went through with the process. This company since that day, it has been deducting money from my bank account every month and yet i have never received any funds from them. Every month i have to reverse these payments(of different amount) because they are *******ly taking money from my bank! I want this nonsense to end or i will take further steps to stop them!!!