Dear Sir/Madam
I am writting to thank you for the superb windows and doors which we had installed by your firm recently. The workmanship and your staff who carried out the work was first class. My wife and I want you to know how pleased we are.

We would like also to thank Mr Hughes for calling to see us before and after the work was completed. I have already recommended your firm to relatives, friends and people I know for the excellent standard and quality of your windows and doors.
Again many thanks
R.T