ISSUE OF COMMON PASSAGE DISPUTE

I have a piece of land 'A' adjacent to a Common Passage (CP). It is clearly mentioned in my land map and deed that Plot 'A' and Plot 'B' are adjacent to a CP. The said 'CP' is not used by me until now because I have my Easement road in front of my plot. But now I shift to the new building which is behind Old building and I want to use the 'CP'. But a third party called Plot 'C' which is situated far behind my plot is restraining me to use that 'CP' as they are claiming that the 'CP' is there own passage and they have sole right to use the CP. 1) The said 'CP' is also used by a Six storey Apartment which has nearly 30 - 40 family and other houses behind our plot. 2) The electric supply company had built an underground 440 cable line under the said 'CP' which is going to the Plot 'C', the Apartment, and to the other houses behind our plot. 3) The municipality had built an underground water supply pipeline and Concrete road under the said 'CP'. What to do?