Can you guys help me with this business math problem?

Hey guys, our professor gave this as our final problem set for the semester but I don't really know how to do it or how to start. Any help would be very much appreciated :)

Here it is:

Mr. Go borrowed from Ms. Sy a certain amount payable at 9% compounded monthly after three years. Ms. Sy required Mr. Go to make regular payments of 9,000 pesos at the end of each month to settle his obligation. Everything went as agreed upon for a year. After the first year, however, Mr. Go missed remitting his monthly payments for five months. In order to make up for his missed payments, Mr. Go paid 60,000 pesos a month after the fifth month of missed payments and made regular installments of 9,000 pesos at the end of each month only for six months. After which he decided to pay Ms. Sy the rest of his loan through three quarterly payments of 40,000 pesos each.

At the end of the three-year loan term, Ms. Sy claims that Mr. Go has not adequately paid the principal and all accumulated interests on the loan. Mr. Go, on the other hand, maintains that he has paid all his dues and has no obligation left unpaid. He adds that he, in fact, has paid more than he was supposed to.

Show how much Mr. Go either still owes or has overpaid Ms. Sy (if any).

(Happy)