Cannot upgrade second box, error TM4/15/10-0-100155
I have successfully requested an upgrade of my box to Virgin 360. The new remote is on its way. However, when I try to request an upgrade of my second box, it fails with "We couldn't process your order", a link to the VM website, and an error code TM4/15/10-0-100155. I spoke to support over Whatsapp, took over two hours, most of the time spent waiting for a reply, only to find out they could not help, and that it would cost me £185 to do this. I said no, it is a free upgrade, and the first one went through okay, with a confirmation email saying the upgrade was free. So, I had spent all morning waiting on and speaking to the wrong people. Horrendous experience.
So, would anyone know about this error code, or have any suggestions? I have restarted the box, with it unplugged for over five minutes, still no joy.
Many thanks.