Effective Date of Resignation

I have submitted my resignation letter dated March 12, 2014 and was supposed to be effective April 11, 2014. Last April 1, I was asked to extend my last day of work until April 28 since the company needs more employees as they freeze hiring for about a month. I hesitated at first since I just want to render the usual 30 days mandated by the company. But my boss, asked me verbally to stay longer with the conditions I can go on absences if I have to for job application purposes and that I can still receive my salary on the 20th of April. I agreed with those conditions stated. Our payday falls every 5th and 20th of the month but is usually earlier if those dates fall on a weekend or on holidays. Last April 11, I was asked to submit my resignation letter with date March 12 but effective April 28. I was fine with that expecting I will still receive my salary for the 20th of the month til I was told last April 12 that there is a slim chance of not getting that pay that was released last night April 15. I was left with no choice since I have already made an arrangement with them. If I wouldn't have accepted their deal and grant them a favor, they would have still held my last pay last April 5 and it will be fine knowing I'll be out in the company come April 11. And it turned out last night that they didn't released my last pay as agreed. Can I consider that 30 days of rendering resignation til April 11 only not on the 28th? It is now against my will to go to work til the 28th because I feel cheated. Can they treat it as AWOL if i resubmit my resignation with a new effective Date and I won't report to work anymore? My reason for resigning is to find another career and because of work-life imbalance. I also have other specific questions for OT unpaid but I guess I'd have to post it with another topic.