What they told you at the hotline is correct.
The Service reminder is set from the factory to 5000 miles. That means after each oil change and service reset, it will go off after 5000 miles again.
After your initial oil change (which is earlier than the upcoming ones due to engine break-in), the person who does your oil change is supposed to CHANGE the service reminder interval from 5000 miles to 10000 miles, which is the interval for the oil change after that first one. I guess that was never done in yours. But a lot of people still run shorter than 10000 mile intervals, just because that seems awefully long.
There is a thread on that in the FAQ in the engine forum. I believe.