Validity of Contract to Sell

Hi! We bought a house and lot property last 2014, we were required to pay downpayment for 6 months. On the third month of paying we decided to cancel the purchase and transfer to a bigger unit. The developer agreed the transfer provided that we will pay the required downpayment which is higher than the 1st unit we planned to purchase. We finished the downpayment last January2015. However, up to this writing the property was not yet turned over to us because it is not yet constructed. We wanted to back out even if the encourage us to continue the purchase because accdg. to them, tentative completion of the unit is on October2016. We also found out that we were not able to sign the deed of cancellation agreement, is the contract to sell of the 2nd unit valid even if there is no deed of cancellation?

Mahirap na talagang maibalik pa ang perang nailabas na, ganun din yun mapapagastos kadin ng malaki sa paghahabol sa cancelation if sakaling naman succes ang cancelation 50% lang ang maibabalik sayo.

kahit ba lumalabas na hndi valid ang contract to sell dahil sa wala naming pinirmahan na deed of cancellation sa naunang contract to sell?