Usage of common path

My father brought a land 10 years ago. When the land was purchased, the owner gave us a pathway from main road to our land which was 20 feet (touching south-west). At the time of our purchase, he did not sell any other part of his property. The 20 feet pathway was the only accessible to us and that pathway stops at out land and does not goes further. Few years back, he divided his land which was behind our land and sold them to other parties. Furthermore he has extended that 20 feet pathway till the end of his land, so that the other parties can use that pathway. Now the problem is my land at the south is 25 meters. The pathway that is given to us is 6 meters south-west. From the 7th meter till 25th meter he has built a wall so that i don't build a gate. Since the south-west is not a good site for entrance we asked him to remove the wall, since outside our land is the common path which he has given for the parties behind. However he refuses. Please advise. How can i use the common path which is given to the parties behind my land?