Hi
I used this type of system both as a contractor and more recently as "a buyer" of cleaning services.
It works very well - I have used a "day to view" diary, a notebook but more recently a specially drafted form (with both organisations logos at the top). The form is simple it just has a date, comment/request, action taken and date addressed.
Whilst it started as a "complaints" book, it is now in all the locations as a valuable communication medium with compliments, general requests and the odd complaint!
Nick