Bg customers expect the earth as bg promises and prides itself on exactly that. They are trusted by the most vulnerable people, elderly, disabled etc to cover their plumbing and heating and to repair it when they need them. The problem is Bg is owned by centrica, a ruthless company only interested in profit. Staff and managers are pushed 24/7 to get every penny they can, every minute they can. This is at odds with an insurance policy, the customer has the insurance policy so they don't have to shell out on repairs and parts.
Just a heads up, some of my most stressful days in the last 20 years were working for Bg, I left 10 years ago and won't work for a big company again.
If you really want to work for someone I'd try a smaller firm in your local area but that has its up and downs too.