Truly a five star service. Sakib responded to the message promptly, assessed that the fix could wait until morning to save a costly out of hours quote. He and his assistant arrived on time, were kind, courteous and got to work straight away - even happy to let me watch and explain what their plan was as they went along. He also suggested some other products I could look into to maintain my boiler system. After testing the fix, things appear to be good as new! Hopeful that the fix is near permanent now. Thanks very much!