Corruption at phed and false information to RTI reply

Sir, Recently I file RTI petition at Public Health Engineering Department, the reply revieled the large scale corruption, which has been going on for last 10 years. I cannot fil PIL because our NGO is one of contractor under PHED to run the TOTAL SANITATION CAMPAIGN progrramme of UNISEF, which is monitored by PHED. I have talked to large number of lawyer in last couple of months, unfortunetely everyone delayed the process. 2nd Question. Recently in one of communal violence, a granide were thrown in vincity of a school, the report were hidden by POLICE and media, the school were closed for four months, and the people were given shelter at Rehabilation Centre. After continuous appeal by public to re-open the school, finally DC, Deputy Inpector of School visited the centre, and order to conduct the class under tree, separately for hindu, muslim and ST students, on opposing the matter by Headmaster of School, because such activities will give bad impact to the mindset of students, Finally Headmaster of school were suspended. Now, after the gap of a year I filed RTI seeking the reason for suspension of Headmaster and delay in re-opening the school, I was shocked to get the reply, which cleary mentioned school closed only for 15 days and Headmaster were absent for 2 months without informing the authority , I also got the infortion that the attendence register were replaced and changed after filing of the RTI. My both the cases are so sensitive, with the involvement of some very high profile and powereful person. I want to send them legal notice, kindly help me with the procedure and saction. Thank you