Agreed, $12/hour is diddlysquat for a 4 year degree. Unless you are off in ruralville or something. They're probably not going to be paying you $30/hour if your area's not a high cost of living area.
At this point though (at least 2 years experience), I don't think his grades will matter for most jobs, just having a degree's good enough.
A lot of times with the big companies, there's a yearly merit review where they'll bump up the pay depending on your "performance". If it is past that time, and you didn't get a raise, start looking elsewhere. Either in or out of company. Review the job listings and depending on your review, focus on in or outside of the company.