Can I file a case against a broker on the basis of credit note

I purchased a flat in Noida Extension through a broker. At the time of purchase broker agreed to pay me back Rs 90000 once I have paid 40% of the total flat cost to the builder and that the builder has released his brokerage fee. He gave me a credit note for this of Rs 90000 where he has mentioned this amount. Now broker is saying that he will only pay Rs 60000 and not Rs 90000.