Dear Mr. Roland,
We appreciated your business last fall and were delighted to be able to serve you and upgrade your water filtration system. We like to follow through after about six months and make sure our installations are functioning at top capacity. Consequently, I have asked our installer technician, Bob, to call you within a few days to see when he might check things at your plant.
Incidentally, we have just received a shipment of a brand-new type of disposable filter insert. Bob will give you a complimentary supply when he makes his rounds.