The cause of action for filing a compliant on the bases of a cheque arose as and when the said cheque got dishonored. According to your inputs of query you are dealing with three separate cheques amounting Rs.2,00,000/-, Rs..2,80,000/- and Rs.2,80,000/- respectively and all the three cheques are got dishonored separately and there must be three separate cheque return memos. It seems basing said three separate cheque return memos you have filed one compliant under section 219 cr.p.c. taking as three offences of same kind within year has to be charged together. The out standing due amounts must be also three separate transactions.
It is the case of the accused that he is having issued cheques to you for your outstanding dues and admits the liability to the tune of Rs. 4.5 lakhs instead of Rs.7.6 Lakhs.
You have very good case and there is possibility convicting the accused.
According to a recent judgement of the Delhi High Court in RENAISSANCE FUNITURE PVT., LTD., VERSUS JEMINI REALTECH PVT LTD AND ANO - 2017 1 Bankmann 303 made it very clear that, "Dishonor of each cheque constitutes separate offense giving rise to a separate cause of action" which is squarely applicable to your case.
Judgments of AP High Courts too supports the case under section 219 cr.p.c if the statuary notices were issued separately.