public servant & public duty

Maharashtra Pollution Control board has outsourced its work of collecting bio medical waste generated daily from nursing homes to some private ltd companies, under some contract for some consideration & allowed them to collect fees from nursing home owners in turn. 1) Under which sections, subsections & clauses of prevention of corruption act do the directors or owners of such pvt ltd cos. qualify as "pubkic servants" & their work as "public duty"? 2) If they demand fees for the period in which they did not collect waste, is it "excessive remuneration" or "illegal gratification" as per PCA? 3) If they say that they will give receipt if such period's unjust fee is paid by cheque & won't give receipt if paid by cash, is it "illegal gratification"? 4) Is the PCA confined only to bribe? Or does it cover all other forms of corruption too? Can ACB act in above form of illegal gratification or extortion? If not can it jointly act with police or district collector? I could not find the word "bribe" anywhere in the act. 5) Can the complainant ask for voice recording CD/memory card/pendrive and other documents to ACB as certified copy? Can complainant use it as an evidence in some other case or private case filed by him if ACB did not act? Or is it so confidential that even complainant can not get it? Is certified copy from ACB treated as primary evidence? Thanks.