You've got a few potential problems in there, some are TV, others internet, and they could be both related and entirely separate.
Ordinarily I'd suggest posting about the internet issues in the broadband forum here but as a bare basic starter - do you have a Broadband Quality Monitor running? If not, set one up - and in either case, post a link to the live graph in the broadband board.
TV - you've referred to a couple of the streaming apps but the TiVo box that you've mentioned doesn't have Prime so do you have a V6 or a TiVo? If you're not sure, check here . The two boxes have fundamentally different internet connectivity so further advice will depend.
Is it only issues with streaming &/or VoD that you have? Or is live TV also problematic?
I'm a Very Insightful Person, I'm here to share knowledge, I don't work for Virgin Media. Learn more
Have I helped? Click Mark as Helpful Answer or use Kudos to say thanks