Stop updates while connected through RRAS

I currently have a RRAS server setup with specialized software that our

sales reps use to receive updates on current products and prices and to

send orders at the end of each day. The process itself seems to work
perfectly, aside from one major problem. Every time a computer
connects to this server (over phone line through RRAS) to attempt a
download or to send orders, the first thing it does is try to check the

WSUS server for Windows Updates. This causes a large amount of data to

be sent over the phone line if there are updates available, and crashes

there transmission of data. When I change the GPO to receive updates
automatically from Windows Updates servers, it attempts to, and is
successful in doing so, reach these internet servers to receive their
updates. Is there a way to stop the connecting computer from finding
the WSUS server even if it attempts to do so, or is there a way to make

the connecting computer stop trying to find a server for updates to
begin with?

Any help would be appreciated. Thanks in advance!