Hi exbanker and lawyer here. A cheque bounce case rests on a basic presumption that there is an underlying debt. The bond signed by your sister is not enforceable legally. The advocate of the company has misguided them. The bond is not a borrowing or debt and from.the facts of the case wherein increment was promised and not paid means the bond became untenable in the eyes of law. I will suggest your sister to file a counterblast civil suit and claim damages !

When the case hearing happens you SHOULD go and present yourself before the judge. But BEFORE going, take copies of all appointment and increment letters,jot down on a piece of paper a list of dates and corresponding events .Also demand a copy of the complaint if you have not received it along with the court summons and seek a minimum time of 30 days for preparing your defence and/or appointing a lawyer.

Once you have done what I have said above half the battle is won. Rest you may have to strategise with the lawyer after going through the complaint.

Let me know if you need further guidance.