I"m not sure what you are referring to when you say that you need a relieve letter...however, if you are referring to notifying the Service that you no longer work for this employer and you want your H-1B terminated....you could do this yourself...as the beneficiary. It is customary for the employer to do this but in your case where the employer does not want to comply then you could certainly write to Service and update your status. Good Luck. BTW: remember you are on H-1B so you technically should write to the DOL as well to the Service...to terminate status. REGARDS!
If you are the beneficiary of an H1-b that was obtained through fraud, then you can be considered to have committed fraud, as well. This can happen even if the employer was never proven in a criminal court to have committed fraud. Immigration is civil law. This means that the level of proof is lower in civil immigration proceedings than in criminal court.
Who claims that a letter is needed from the employer? You may need to seek a waiver if you are banned from coming back to the U.S. on an H1-b visa. Such a waiver, if required, can take time and may prove unacceptable for another employer, but this is unclear. It is also possible that a waiver petition can be denied.
You may want to contact the Department of Labor and file a complaint for lost wages against the H1-b employer. You may also try to file a complaint for witheld wages in the state where your employment was supposed to take place according to the labor condition. However, it is unclear whether you waited too long.
I recommend that you schedule an appointment with an experienced immigration and visa attorney. However, I agree with my colleague that a 'relieving letter' seems a bit unimportant at this point without further information.
The above is general information and does not create an attorney-client relationship.