Voicemail timestamp off by 3 hours for over a year now.

I have been having problems with the voicemail time stamp being off by 3 hours for over a year now.  I've tried changing the time using the voicemail menu. I've tried changing the time on my phone hardware. And I've tried changing the time online using phone tools. Nothing works. When I changed the time on my phone's hardware, I actually thought I'd fixed it but as soon as a call came in, it reverted back to the incorrect time.  I've reset my modem a number of times which had no effect at all.

This is the second post I've written. The first one has been locked so I can't respond to the person's question.  

Please help me figure this out. It's really getting old.