Contract rescission

[lynx2002]

CHF International is a Maryland, USA based NGO which has a local office in the Philippines. CHF Philippines contracted to us a baseline research study regarding a database software they developed for use by the government Cooperative Development Authority (CDA). After completing the results of the study and receiving 80% of the payment, CHF Philippines refused to pay the remaining 20% \"rescinded the contract\" because they said they cannot use the data resulting from the research. We have strictly followed the terms of the contract through regular direct coordination with local staff and obtained their agreement on the courses of action to be taken as well as responded to their comments. We believed the output was consistent with the requirements of their Statement of Work (SOW) - their equivalent of terms of reference. If they cannot use it, as they claim, that is not our fault and we should be paid the final 20%. What legal action can be taken on this matter? If it's arbitration, what venue is available to discuss this? Thank you for your opinion. Good day.