Handling Mistakes w/ ISP Billing?

michael asks: "I am having a problem getting AT&T to find a cheque that I sent in. According to my bank statement it was cashed on April 12 of this year but it did not get applied to my account. I have been dealing with AT&T about this since then and they have finally cancelled my @Home service. I have faxed in copies of my bank statement and my cheque. I have phoned, e-mailed, mailed, faxed many times over the past four months trying to get this resolved. Only once have I been contacted by a person since this issue began. They requested the copy of the cheque - I had my bank fax a copy of the cheque to them and to me. Almost all other communication has been one way. I contact them, they leave me hanging. I get the occasional computer generated bill saying that I own them money, but that is all. What are my options here? Do I have any?" Sounds to me like all of the right steps were taken here. What else could Mike have done in this situation? Why is it, that in today's info-culture that things like this can still get lost between the cracks (and this problem is not solely limited to AT&T, either)?