This is primilarily a user-based forum where other Virgin customers (for that is all most of us are) help each other out, and VM staff come in after a week or so if they're needed.
It sounds as though you've already been in touch with faults-CS and they've booked an engineer visit for you? In which case that's the best course of action. If there was an area fault they'd not picked up on.. then affected customers all booking tech visits would see to that 😉 Equally it's possible your box has just been "kicked" into a faulty state by external factors, in which case the tech visit should see it replaced.
Short of powering the box down at the mains for a short while to "cool it off" and then rebooting from scratch, there's probably not a great deal more you can do.. more's the annoyance for you, I'm sure.