Dear Sirs,

Your technician called today, and was very thorough and helpful, despite the fact that there appears to be nothing wrong with our heat storage unit as he suspects that one or more mixer valve(s) is to blame for the fluctuating hot water flow, and we cannot locate where they are.

I would like to record our appreciation of Ross – I cannot recall ever having so helpful and polite a young man come to our house to carry out a job. He is a credit to himself and to your company.