Unfair Set Off of Arrears for my cheque account

My account number is ********** 588. An amount of R16522.67 with the reference s/o VMFB20617 was deducted from my account on the 19 December 2018 without my permission. I was only left with R5028 in my account, the amount deducted was for the payment of my homeloan and buying of groceries for the current month. I understand that I am in arrears with my Vehicle Finance but I contacted them in November with no avail to enter into an affordable payment arrangement (I have the email I sent in my possession), instead of entering into an affordable payment arrangment with me, MFC chooses to ***** all my money meant for living expenses? Can someone please urgently look into this matter and kindly refund at least enough money for the payment of my bond which is R15 938?