You Broadband - Promised package not delivered

Hello Sir/madem,I'm a you broadband customer from more than *yrs.Recently I'm not satisfied with their service and tried to change my network provider.But they conatcted me regarding this and i was given a return commitment regarding their internet plan which is ""If i paid some ammount and get renewed my plan with them,then they will give me extra ** days offer along with their normal plan.""But from **th of this month they stopped my internet stating that my usage days are over though the extra ** days offer is still left.When i called them they responded that their executive has done some fraud and i need to contact their executive regarding this who left his job.I conveyed the same to them but they did not gave any response and they are not in a mood to care about this.I'm also attaching the photocopy of their company bill.Please solve my problem Sir/madem