I'm sorry to hear about your trouble with ordering a new TiVo®.
I have tested this from my side and there doesn't appear to be any issues with the online system at present.
After hitting "book delivery", you'd need to input the following information:-
If you are still having issues with this, the team will be more than happy to assist you further on 150 free from any Virgin landline or 0345 454 1111 on any other line.
Alternatively, you can chat to our online team via: [Contact us].