Worst service ever....

For the past month i am struggling to get throw to the finance department. For the past two months the took of instalments that i dont understand where they get it from. When i email they send a email back that they are receiving high volumes of emails and they will come back to me. What a joke, they must just pick up their phones and solve the matters. If this problem that i have is not sorted ASAP then they must take this system out because if they cant just solve a small problem how will they get back a ****** vehicle. I dont have anything against Altech Netstar but what must i do to get hold of someone to help me and to look why they take of the wrong amounts on my debit order.