[sdeming]

This is not a good explanation. I would ask for MRTG graphs that demonstrate the traffic coming into your port on their switch.

Basically, if you shut the game services down then they are not responding to the requests and your traffic will illustrate this. Your inbound traffic may still be greater than 0 but your outbound should be near 0. Even so, your inbound traffic will fall dramatically since no connection is maintained and the typical resulting conversation between client and server does not happen.

Bottom line, if you typically pushed/pulled near 5 GB per day and are still pushing/pulling nearly the same amount after shutting down the game then something else is happening. What you may want to do is run tcpdump and get a capture of the raw data coming in/going out. I am willing to bet that you will not see that much. Force your provider to give you access to the MRTG graphs for your port. It isn't enough to take their word for it, they have to be able to back up their claim. If possible, ask your provider access to the SNMP community (read only access should be provided without any concern) on the switch pull the data yourself.