Thank you for all your team's hard work in ensuring our warmth again!
May I take this opportunity to thank you and your engineer for the prompt response he gave recently.
A prompt and efficient service with a very polite engineer.
Many thanks to you and your team for the (usual!) prompt attention.
Thank you so much to you and your team for the speedy and neat fitting of the new boiler and...
Thank you once again for responding to our hour of need. The system is now better than it ever was!