Giving NOC is always negotiable, it is always depending on you on how you will discuss and ask for it from your HR Manager or Sponsor. Laying all your cards especially your dues to the bank will help you, sharing your responsibilities back to your home country, making a drama just to get your NOC. Offering your sponsor an alternative or other employment offer to you from other company might be taking into consideration. Offering not to get any amount from your current sponsor in exchange of having NOC can be discussed discreetly and diplomatically is also another option. All company rules can be broken depending on how you will approach them. In Worst scenario if all mentioned options didnt work, then check it at Labour Office at Industrial area.