Similar case here!!!
They charged me hundred dollar more since the contract start in Feb.
Called them at least 5 times for this issue and I asked them to send the detail bills to me months ago.
As I have to BF my infant by that time, I can't talked to the CS for that long, so I asked then to give me a call afterwards. Hahaha...they just simply disappeared. And no more follow up call ever appear.
Then I try to call them again today. Hahhaha again...the line just got disconnected suddenly when I wait for them to confirm what plan I have joined.