Internet has been up and down as per and now only one Tivo box is showing all the channels.
Have you tried following Home > Help & Settings > Help > TV Care > "I'm missing some channels" to send a refresh to the affected box? Not sure what you mean by your internet being "up and down as per", but if you've got issues with your incoming signal levels - that will affect everything downstream of that, TV & broadband included.
Also next door neighbours have the same package as us and there bill is half what ours is. HOW DOES THAT WORK.
Quite easily - different accounts can have different discounts or loyalty offers on their account, or may have renegotiated their package at some point. If you're outside your minimum term, you can do the same.