Window sash cord and nightmare contractors

[Jeffrey Giffin]

Hello BP members.  I am hoping someone can help me out here.  We hired a nightmare contractor to work on some rehabbing and while they were in the house they mangled one of the window sash cords on one of the windows.  So I asked them to come back and fix it and this morning they come over to the house, cut the cord and say it isnt needed because it has one on the other side and leave.  I unfortunately dont know anything about windows but I am thinking if it wasnt needed it wouldnt have been there in the first place.  Any advice would be greatly appreciated.  Thank you!