I fit exclusively Worcester Bosch, all boilers will eventually breakdown, but my extensive industry experience over many years tells me that they are by far the most reliable manufacturer.
I would always recommend fitting a system filter, statistics show that they prevent breakdowns by approximately 20%,
flushing the system out properly and adding chemicals will help prevent problems occurring in the near future.
Updating the system at the same time, for instance, new controls to improve efficiency, The Hive or Nest can give greater control and accuracy improving your energy bills. Thermostatic radiator valves are a necessity as per building regulations, again this can improve comfort and efficiency.