Road not constructed

A house (A) is being constructed before my house(B). Between A and B there is road. We purchased plot B from colonizer who gave us approved map in which there is 30 feet road between A and B. At the time of approval of colonizer of A there was approved road of 40 feet. As colonizer of B has got approval of B among other plots after approval of A among other plots, colonizer of B got approval of 30 feet road. At present there is 30 feet road but before A and B there is no pucca road. Among other plots there is pucca road. A has been allotted patta by nagar palika marking with ABCD and mentioning area in the patta. If there area is measured they come over and above the marking area ABCD. That is they have to capture road between A and B by 20 feets and leaving vacant area for road only 10 feets. Our question is that whether they can encroach the road area and if the patta by nagar palika is issued wrongly then can we file suit for cancellation of patta as they have measured area of road also in measurement. Our colony approve map is of 30 feet and at among other plots there is road of 30 feets then what should we do to save our road of 30 feets.