Land Encroachment suspected and Panchayath given Approval without following the Building Rule

Hi, The issue is relating an property Owned by my father. We have a property which was inherited, but we do not leave nearby. Our relative has constructed an house in a plot adjacent to the access to our property. It was given permit and Number. But when we were planning to sell our property we measured our plot and found out they have build house encroaching the access road to our plot and also not maintaining the Building rule and required Offset from the access. The access road was obtained from them prior to building of their House. When we obtained the building plan and details through RTI from panchayath we got to know in the plan given for approval they have shifted the location of the access to get the required setback. Moreover, they have claimed to have more land in the plan than what they have in their document to get the plan approved. We had given the complaint to panchayat, but as there is a mistake from their side in approving a faulty plan they are reluctant to take action and dragging the complaint. Currently I am not able to sell the land as there is no proper access to the plot. How Can i proceed? If I got to court, will it be required to produce the original documents, currently we have only attested documents from bank as the original is submitted to bank for Overdraft purpose.