Poor customer service & payments service

I have had motor finance with MFC on my Toyota Runx for the past 5 years or so. I recently paid the debt of in full, but paid extra into the MFC account due to me having a scheduled payment in place. My final installment was paid in full. I then reported to MFC that i needed the monies owing to me be refunded as soon as possible. They asked for proof of payment , so i sent them my bank statement as well as proof of payment and the payments that i made. I did mention the urgency of money to be paid to me. I was informed that my paid up letter would be received with 24 to 48 hours. i haven't recieved that , i was inform that the refund would be made by 5 or 10 days , that has not happened as well. I spoke to Karishma from the MFC on Friday which was the 15th and she said that she would escalated the payment so that i get paid on Friday evening but that never happened. Today 18th of April i received a message from MFC requesting my banking details so that they can pay me. I need to be reimbursed for that 18 days of which my family and i have had to struggle due to their poor customer service.