Go to Garmin's website (garmin.com), and look under Support - Contact Us. there you will find phone numbers, both standard as well as toll-free. Based on my past experience, be prepared to wait on the phone, but when you do get a live person, they have a reputation of being quite helpful.
I second the be prepared to wait. Figure at least 30-40 minutes. If you get through quicker, it's a bonus. I always get my questions answered and hang up being very pleased with their customer service.
I bought a GPS off e-bay in 05, and didn't realize I had to register it, or the previous owner had to let Garmin know that he sold it to me. So when I wanted to get the updated maps, Garmin had no record of me being the owner, even though I had all the un-lock codes and all the other #'s they needed. Garmin said they would have to get ahold of the previous owner to release ownership to me, so I could update the maps. After many months of trying to get ahold of him, I did a Goggle on him and found he was serving 51 months in federal prison for securities fraud and income tax evasion. Great! After spending 3 + hours on the phone with Garmin, and faxing them all the stuff I had, including the article of him being in jail, they finally gave in and I got it registered in my name and purchased the update. Now you think that would be the end of the story...but NOOOOOO.
Once I got the updated version, I could not get it to load, and after another hour on the phone with Garmin, I find out the update is on a DVD, and of course I have a CD in my computer, and a DVD wont play on a CD. So out I go to buy a DVD, and I finally got it all updated and down loaded to the GPS unit. Now I can find my way anywhere. I also made a back-up CF card with all the maps loaded.
Call as early in the morning as possible to avoid a wait time. Your registration code is located on the unit so you can register it that way but you will need your registration code that goes with the serial number.
Never throw the box away until you check everything and keep it in case you have to send it back for repair or replacement.