Thanks for posting regarding your TV service connection, I'm sorry to hear you have had some issues with the picture on this.
Could you let me know if you are still having this issue?
If so, have you been able to check all the connections are in tightly. Picture loss with sound coming through sounds like it might be a loose or damaged cable issue.
If you have tried this already you could also try a full reboot of the system. If you'd like to take a look at our Help section there's some great self help articles on troubleshooting your TV service available here. They might help you out too.
If you can get back to me to let me know if you've tried the above and what the results were i'll do my best to assist further if there is still an issue.