Full and final settlement of dues

Dear Sir, I am working in a private firm in Bangalore in senior management team. After having worked in the company for over 12 years and I have resigned the job and I am now serving the notice period which ends on 25th August. I have been given by the company my settlement benefits letter which includes gratuity, leave encashment, bonus for last year and bonus for the present year till the last date of my work. I have my concerns over the company paying me the settlement dues since they havent paid the settlement to two of my colleagues who has left six month back and another last month. The company had earlier in 2006 sent out a policy via email in which it is mentioned that the full and final settlement to be make before the last day of discharge. But this is only in the mail/attachment. The company has told one of my colleague that they would withhold the bonus amount and they would pay it only when other get paid (no specific time). Is this correct when the employee is leaving company. Shouldnt they pay all the dues... If the company fail to pay me in time or just plays around it how should I take this forward legally. I sincerely request your kind inputs on this please. Kind regards Bopanna 9845070093