MFC - Taking debit orders incorrectly!!! Do not use them for finance.

MFC keeps accusing me of being behind on my hp loan.... but I'm not. This is now the second time it happened. In October they took 2x debit orders from my account, when I queried it they said I was behind as a previous months d/o didn't go off... This is not true and I mailed them all my bank statements to prove it. They only refunded me in December. Now again in Feb they took 2x debit orders and are saying I'm behind .... I'm not!!!!! So what now will I have to mail them again to prove it...and again wait two months to return the money they took incorrectly....??? This is totally unacceptable! The joke is that I bank with Nedbank.... and MFC is a division of them so why must I jump through hoops to prove that I'm right.... I would not recommend that anyone use them for finance.