I had booked a service for my boiler with SI and was given a 2 hour window on a Saturday Morning as requested. I received a phone call in the morning to confirm the appointment and was given an exact time within the original appointment window. The engineer arrived exactly on time and was very polite and respectful.
The engineer carried out the service and explained what was being done. He had put down his own dust sheets and used his own vacuum cleaner and kept the work area clean and tidy.
I would highly recommend SI Gas Service & Repair as they were reliable, punctual, competent and tidy.