We unfortunately can't see you bill, but are you able to log into Self Serve to get a .pdf of your bill? If you can provide a screenshot of your e-bill (with your personal details editted out, please) we can at least help clarify the charges.
If it's concerning Data overages, it'll be a question of whether or not you can "prove" you used less than their system shows.
Try to remember to stay calm when speaking to them on the phone. They talk to a lot of people so a calm conversation goes a long way.
As for ways to "prove" it, it's happened to me a couple times & I sent them a screenshot of the data tracked by my phone VS what it showed in their systems. Both times they reversed the charges.
I can't guarantee they'll reverse them for you, however, if it's the first time, you're calm & polite and you can show a discrepancy using an App, I'd say you have a good chance.