Drain issue

For the last 42yrs, my drain has been connected to my neighbour's drain on the east as they have a long stretched drain right from south to the north adjacent to our land which ultimately connects to the municipal drain (north) (Topography of the land is such that south is elevated and water would naturally flow towards the north ).. however of late, the old neighbour sold off his land and that the new occupant of the land has blocked my drain citing that it is not correct that my drain is connecting to their drain and that i should look for other alternative... we had several rounds of heated conversations and also complained the municipal office... the municipal office is saying that since it is their private drain municipal cannot help.. there is no municipal drain nearby.. the only municipal drain is in the north . And if i have to connect my drain to that municipal drain my neighbour on the north has a problem that all these years it was passing from the other drain. What is the solution to this ?