nomerci is right there are lot of people who are victimized and abused because of this process in your situation it is difficult to transfer in other company if they will not provide NOC its there discretion, now if your planning to go home in your country what is the assurance that the new company will issue you a working visa? because its a lot of process and it will cost a lot time and money to them not like if they will hire people who are here already so its your choice. Goodluck