The best time to phone is first thing on a morning at 8am when lines are least busy.
You could also try the text messaging service. Just send a text with a description of your problem to 07533 051809. Your message will go into a queue and a representative will respond to you as soon as possible. It may take a few days.
You could also post any error messages you are receiving and see if a member of the forum can help, or after doing that leave it a few days for a member of the VM Forum tTam to pick up your post.
The Service you do for others is the rent you pay for your room here on Earth - Muhammad Ali