Hi, Got a vokero flowmatic 20-80 combi, considering a new boiler.I notice worcester are not top rated, anotherVokera is or Valiant. Any assistance appreciated, on price and whether to opt for other make/model?15+ years old, pilot light.Is it G band and qualify for £400. Can I opt for boiler of my choice if I use Eaga warmfront?or go for independant installer and get £400?cheers