The absolute first thing to remember is to remain calm while dealing with this. Emotions can make this uncomfortable situation worse for you. So in any interactions keep calm, ask questions rather than making accusations, and solve the problem rather than burning the bridge.
I would get on the phone (not an email, but a phone call) with the hiring manager. Ask what specifically what criteria were given to your company that disqualify you as an employee. Further, ask if would be able to provide verifiable records, if that would alleviate their concerns.
When you make this call you must be polite, patient and respectful. Of course, you should be these all the time anyway (especially working as a customer service professional!!) but the things your hiring manager says will probably upset and aggravate you and you can't let that happen. You need your hiring manager to fight for your place on the team or you will not be getting this job.
Emphasize the fact that you were hired based on your skills, experience and education and they are all verifiable. The company performing the background check must have made some kind of clerical error. Make sure to use phrases that talk about your future with the company - it's a powerful message that you're committed to getting through this blocker.
That being said, I wouldn't trust someone with their own proof of education. I would want to see it coming from the institution itself (and I'd be willing to pay for a certified copy delivered straight to me.)