Physically wrong plot adored as per approval sheet by TLR

I purchased plot no. 38 but as i proceeded for construction on the n.a. plot found out as per approval sheet by tlr that my said plot no. 38 ia actually supossed to be in loction in plot no. 39. according to the approval layout sheet my plot shows a box figure in my plot. 38 which stated in approved sheet thay there is a structure on my plot, which actually has a pump house till present date. According to this finding we came to know that plot. no. 39 is actually my plot as per proper demarcation. The vendor was Confronted and even admitted to this issue. He is stopping me from getting the land measured by city survey to do the necessary correction. As of now I technically encroaching the next plot as all the plots have to move 1 and half plots ro the right side as per correct measurement. All the plots has to be relocated As per approved sheet by TLR. Please help as the vendor is trying to ignore the situation and tells me to stay as is, there is nothing to worry about. HOW CAN I CLAIM MY RIGHTFUL PLOT.