Payment arrangement denied

Last week I sent a WhatsApp to planet42 to request for payment arrangement just to skip this month payment and I will pay it in 2 installments from July. Only this month as I'm relocating back to Soweto from Pretoria. I was told I owe the month of April which I was not even aware of. I checked my statement and I realised they didn't debit and it reflects as a credit how I don't know. I sent them a screen shot showing that I had money in my account so why didn't they debit, I didn't get a response for that but they responded to say they can not help me with my request. I have never skipped a payment and just one request and I am really in need of money just for this month but I'm denied the arrangement. How do they look after their loyal customers??? Please I need your help and I really don't want to loose my car.