It appears the department has given immi s57 (Natural Justice Letter) and you haven't provided a satisfactory reason to support your claim and visa refused as a result of verification failure. If you have not given the right to review the refusal, you probably might be banned for 3 years under PIC 4020.
Excellent, you can ask your sponsor to lodge a review with AAT. It will cost around 1K but will definitely worth it. If they decide the decision is wrong they will refer it back to the department for reconsideration.