I'd post the picture and explain to GM what you expected from recall repairs, the place you went to, and show them picture showing you got what amounted to a cheap band-aid fix.

It's no different than a doctor who slaps a band-aid on a patient, then billing his insurance for X-Ray, CT scan, EKG, EGG, urologists, head shrink, 20 different kinds of medicine, and 8 hours of labor with assorted nurses and doctors. If the repair you got is not what GM was offering, then the stealership doing the sloppy job cutting corners can be denied future repair services due to safety issues and fraud, and even lose the right to be a GM service.