How to order XER10?

I ordered multigig (2gbit symmetrical) fiber to the home.  Tech came out with the 10G ONT and an XB7, which means I am stuck at 1G ethernet speeds.  He said I would need to get an XER10 from support/a store.  How do I do this?  None of the stores seem to have it.  Tech says XB10 will not work and I need the XER10.