Thanks for the reply, Scott.
I see there's the option to just pay to renew for x number of years via the control panel - would I be better to do this to cover myself rather than risk the domain expiring?
I just don't want to incur the huge cost of recovering the domain if this technical issue does cause it to expire.
// quick edit
I just got a message from the billing team on this issue - due to a bug I do indeed have to do it via the control panel.
Thanks for the help anyway.