Windshield Wiper/washer Linkages problems of the 2003 Ford E-550

My wife has a 2003 mustang and I have a 2003 f-150 truck. Both vehicles have had the windshield wiper blades replaced mainly on the drivers size many times . They go bad within a month or two causing them to bonce across the window ,when this happens you can hardly see, the dealer says you need to change them once a year but as you see it is many times a year . We use a 2004 f-350 truck in work that is doing the same thing .