Verbal agreement with money involved

Hi, i just need to know if there is such thing as breach of verbal aggreement? I payed earnest money on a property being sold to me. The owner of the property is my wife's relative. The seller is my wife's cousin but the property was name under her father. Since her mother died they left the property and transfer to another area. She have 1 sibling. Since shes the only daughter his father chose to give the real estate property to her. The father and daughter is now residing outside the our country which is why i dont have the signed contract yet cause we agreed verbally that the daughter will personnally return here in the philippines to collect the full payment of the property being sold and for the contract purposes too. Her brother also refuse to participate in the deal cause as he told me that its his sisters property already as they have agreed. The sister then ask me for an earnest money of Php 20,000 to be given to her brother which i complied by sending it to palawan express padala courier. We have agreed to meet by march 2017 for me to pay 50% of as we agreed and the remaining 50% Later this year upon the arrival of her father for the signatures needed for the transfer of docs as it was under her parents name. Just 3 days ago she told me regarding the change of agreement and that she was advice by her aunt that i should pay them a much higher price than to what we have agreed and her offered price before and that i should immediately pay 100% prior to the arrival of her father. What sort of thing can i do to correct these? The property was located in mindanao, i have already purchased a back and fort plane ticket november last year and arrange accomodation for the agreed schedule which is march 2017 only to find out they are backing out of what we have agreed verbally and almost tripled the amount of the property from the original agreed price.
Hoping to hear any comments and advices on this matter.

Thank you and more power.