Complaint Review: MCI Worldcom Wireless

I had two MCI Worldcom Wireless phones with $29.99 plan. Their billing system was so messed up and I get bills for August in November. In effort to update the billing system, they've been omitting phone call details. I'm supposed to get detailed billing if I sent the request, but I didn't get it in time. Even thought I sent the payment, it gets posted so late that I always get past due notices.

If I had other company's cell phones, I would be paying about $80 including taxes. However, I'm sitting with more than $1300 phone bill!!! It's outrageous. I tried to talk to customer service, but it's almost impossible. It seems that no one is ever there. I e-mailed them several times, but no one replied.
What Should I do??