Hope you get your issues resolved.
A few years back, I have a story regarding AT&T Wireless (now a part of Cingular). It wasn't actually my own problem. I follow my minutes quite closely and have never gone above my monthly minutes.
This story is in regards to my ex-girlfriend. I guess not all plans at the time were nationwide for AT&T so before she went on a trip to Seattle, she stopped in a local store to make sure she could make calls without being charged extra. They told her yes so she used her phone in Seattle. The next month, she got her bill and it was over $600 with roaming charges.
Basically, all of the customer support representatives she called said tough luck. Since she didn't get anything in writing from the store, they couldn't do anything because they couldn't trust her word. She went through about 10 customer support representatives, some who would even hang up on her. I searched on the Web and found it was a common problem and that nobody had been able to get their bills refunded.
I kept searching and finally came across a news article about a special customer support division at AT&T Wireless for VIP customers. I guess if you are a large account (say a business) that brings a lot of revenue, you get special customer support. I managed to find the name of the Senior Vice President of that division and figured out his e-mail address through trial & error. it's usually something like
first.lastname@domain.com or
firstlastname@domain.com.
He actually responded and said he would get someone in his office to resolve the complaint. Finally, someone contacted her and offered to take it down to half the original bill. This was unsatisfactory so I e-mailed the Senior VP again and finally got all of the extra charges dropped.
It was a big hassle and I think we got really lucky on that one.