<human>: Can you condense the text into a few key points?

My girlfriend's 2001 Nissan Xterra's alarm started going off for no reason a few minutes after walking away so we had to disable it.  I've Honestly never owned a car with an alarm so we took it to a car stereo place in town to get it disabled.  Her clicker (key fob) is after-market which they said was causing the problem and that because it was a stock alarm in the car just unplugging it would also be unplugging all the lights and horn on the car.  He said they would need to "reprogram" it and that it would take about an hour costing $75.  I've really only owned older, mechanically simple, cars so I'm not sure what I'm talking about when it comes to alarm systems and engine computers (not even sure if the 2001 nissan xterra se has an engine computer).  I seem to be failing when it comes to google research so I thought I'd try to get some help here.  Thanks reddit!
<bot>: 2001 nissan xterra se with stock alarm and aftermarket key fob.  $75 to disable alarm sound right?