Customer Service Nightmare about Billing

This one is going to be a long post because it has been a 6 month problem.

Back in February 2015, I received my paper bill, but it was actually a duplicate of the previous months bill, as to date of services.  I called c/s asking for a corrected bill.  After a long discussion and them telling me that what I was describing as being impossible, I finally got them to email me a corrected bill.  Then the next month, no paper bill arrived.  Again I called c/s asking for them to send a bill.  This time they blamed it on the post office losing my bill.  Again they emailed me a bill, which i promptly paid.  Once again, no paper bill was received.  Again I called c/s telling them of the problem.  After verifying my address YET AGAIN, they assured me that they would make sure I would receive a bill in the mail.  Of course I did not get one.  Again, I call c/s telling them again no bill was being received.  Again I verified the address, which somehow or another had been changed (I have always been at the same address since service was started).  They ask if I wanted to pay online, which I declined.  For my accounting system, I need paper bills mailed to my business.  

I informed them this time that I would not be paying the bill until I received a bill from them.  I figured (correctly it turned out) that if I let my account get delinquent, that a bill would be sent.  I was told that I would receive credit for the late charges that were being added because it was a problem with their system.

Sure enough, the first actual bill I received was for three months, but with a $9.50 late charge added to it.  I promptly paid this bill, but deducted the $9.50 late charge that was suppose to have been credited to my account.

On my next bill, the $9.50 was again on my bill.  I called c/s yet again on this explaining that with what I sent, plus the $9.50 that should have been credited would have cleared my account.  The c/s agent tells me that because I did not pay the $9.50 that I did not owe, another $9.50 was applied to my bill.  After another lengthly discussion which I was told that they could and would not credit back my account with $9.50 and being put on hold for over 20 minutes after I requested to speak to a supervisor, which of course was not available, the c/s rep came back and told me that they would do another credit of this late charge back to my account, but this would be the absolute last time they would give me any kind of credit.

Now the new problem.  Since I had already sent in my regular monthly bill amount (minus the $9.50), yet another, according to the c/s rep, will be applied to my account and there is absolutely nothing that she could do about it.  So we are back at the beginning again.

I have never in my long life had such a problem with first of all, getting a bill and second of all, getting a problem corrected with a c/s department.

If anyone has any ideas how to fix this or who to contact when c/s can't or won't help, I would love to hear about it.  I have spent entirely too long on what should have been a simple fix.