I’ve had some work done on my face and it looks great but now my neck looks really wrinkly and saggy in comparison. What sort of procedure addresses problems like this in the neck?

One option is a surgical neck lift.  This procedure is designed to address any excess fatty tissue of the neck with neck liposuction, address weakness of the neck muscle and/or bands of muscle in the neck with suture and tightening techniques; redundant skin of the neck can also be trimmed during this procedure.  A laser-, ultrasound- or radio frequency-based procedure may address skin laxity of the neck; however, if there is significant wrinkly/saggy skin of the neck, the surgical procedure may provide a more effective, long lasting result.