Hi,
Try using this trick it might worked. It worked for me but the catch was the employer generated a pay-slip but never mailed it to me. I did recive the faxed copy of pay-slip which I could atleast use to transfer the H1.
Send an email to atleast 3-4 people HR, your supervisor saying that since they are not sending you last pay-check you are thinking of taking a lawyers advice. Probably they might send it. Is your employer a Indian company? They always give you a reson that the client was not happy with deliverables. I am planning to file a complaint with DOL.
Let me know if it works for you. Did you check the case that was recently posted on this website about employer Synergy being banned from processing H1 since he didnot pay to 2 employers.
Thanks
Anu