took money but I'm behind on payments

I have joined adcap in April this year since then I received a monthly instalment that I have to pay. I recently received a call from a legal firm that they will have to take my vehicle because I am behind on my payments. So today 30 September 2015 I received a call again from the legal firm that on 6 months time adcap have only made one payment on my vehicle instead on the agreed amount every month so I have to pay a ridicules amount today other wise they will have to take my vehicle. I have phoned my relationship manager and she said that I must pay that money because the bank accepted the wrong offer they made so is it really me who has to pay the money but in 6 Months time where did the agreed upon money went to? I'm not filling in the exact amounts of confidentiality. If I could be assisted ASAP.