OK. I just had a quick look at the addon code. If you already have it installed and it was working except for you getting cut off after too many calls I may be able to help.
I think you are only allowed to make a maximum of 150 calls per day. This script seems to call every 180 seconds, which means you'll use up your quota after it runs for about 3.75 hours.
Looking at the code the main thing I would try changing is the value of 180. You may have to wait until tomorrow to try it, or you may be able to fix it by getting a new IP address if you can do that (sometimes you can reboot your modem to get a new IP, depends on your ISP etc.)
The other thing which is really stupid, unless I am reading this thing wrong is that it is looping constantly once every second.
I would change the sleep line to 30000 (30 seconds)
and I would change the 180 to 300 (5 minutes).
or course it might make more sense to just increase the sleep to 5 minutes: xbmc.sleep(300000)
I hope it helps. Here's the original code (from the file: service.py) with extra stuff removed to make it easier to see what I'm talking about. Just go into the addons folder, find this file and edit it using notepad or something, then restart XBMC.
...
...
class XBLMonitor:
def runProgram(self):
self.last_run = 0
seconds = 180
...
now = time.time()
if now > (self.last_run + seconds):
gamerTag = ADDON.getSetting('gamertag')
......
xbmc.log('XBLFriends: Monitoring disabled')
break
xbmc.sleep(1000)
xbmc.log('XBLFriends: Notification service ending...')
...
