1. Have you already made payment of 20%?
2. You should have conducted property search before deciding for buying it whcih you have not done,
3. The company can not offer to sale a property which has not yet been sanctioned by the competent authority,
4. The builder or its agent also can not force you to take loan from their chosen lender,
5. Send a lawyer's notice claiming refund of the amount byou have paid with damage for cheating you by collecting advance payment supressing the fact that the plan of construction of the property was not sanctioned at all,
6. If the builder or its agent fails to act, You can file a complaint case alleging deficiency in service and unfair business practice claiming the said refund, interest, damage amd cost.