Remove Add-In In 2007

I've been sent a document by a client which has come with an add-in which has automatically installed itself into the Ribbon. It's on the Add-In tab (obviously!) and the Command Group is named 'Custom Toolbars'. What's annoying is once I close the document, the Add-In stays there and I have a redundant tab with an irrelevant Command Group .

Now, I've done a bit of searching and how found a number of websites that give instructions on add-ins. However, the add-in that has come with the client's document isn't on the list and hence I can't remove it. I need to do to get rid of this? I've contacted the client, but they're suspiciously quiet about the whole thing.