Do you sit in your reserved seat on trains?

I feel like that kind of stuff happens a lot. I travel to Edinburgh from Manchester quite regularly, and half the time my train will either be seriously delayed or cancelled, or it will get cancelled halfway through the journey and you have to get onto another train already filled with people. It's unfortunate as train tickets are very expensive.

I'm normally travelling from Cardiff to my home town (in Sussex), and I always find that whilst Southern are always pretty good with service, I will inevitably have a problem with First Great Western. I don't know why their service is always so poor, but it's always them.