Hi ionicwoman69,
Thank you for reaching out to us in our community and welcome, I am sorry to hear you are having a issue with a crackly line, I have had a look at things our end and cannot see any issues at all.
You can run further checks yourself via your online account, there isn't a charge to send out a technician for a fault however it the issue was due to the junction box you replaced then there could be a £99.00 call out charge which is at the discretion of the technician.
I have arranged a technician for you, you can view and manage the appointment in my virgin media under my appointments, if you no longer wish for a technician you can also cancel it there.
Kind regards
Paul.