Unpaid Salary loan from a cooperative bank.

Hi atty. I need a legal advice regarding my problem. I had a salary loan last August 2011 from a cooperative bank in cagayan de oro. I loaned 45,000 but I only get 41,000 because they deducted for some of the service fee. I paid and sometimes the payment will be delayed due to some problems. I worked in a BPO industry and I paid monthly. from I guess April until August I haven't paid them because last April of 2012 I sopped from my work. Then I was told that if I can't pay for it they will file a case against me. I told them that I will pay them because I will be back for work. Now, my mother paid 2000 for september and 2000 for Oct. Now they are texting me that I will be paying 21000 all in all for those m,onths that I did not pay. I already talked to the manager that I will be paying for it every month. My due is on Aug. 2013. What should I do they are texting me again to pay for it or else they will file a case. Please help me.