Refund for flight to dangerous city with the U.S. State Departments highest rating

Booking # 49628893.  I want a total refund.  The companies above are trying to force me to travel to Managua, Nicaragua.  There is ongoing dangerous rioting against the government and an advisory travel ban from the U.S. State Department urging U.S. citizens not to go there.  chespOair told me once the ticket is issued it is the airline's responsibility ; the  airlines said I bought the ticket from cheapOair, talk to them.  I talked to a cheapOair rep several months ago and was promised a $75.00 refund and a $75.00 coupon from the airline as my partial refund.  I have received nothing.  I want my money back!  What I paid for the  original ticket and also the change fee I was charged because I could not go there at that time for the same reason as above.