The company I work for does lots of service work and we approach it like this.
A customer who wants an estimate for a repair is told that we can't do that over the phone. Either we come and fix it for T&M or we refer them to someone they might prefer. When we are called for other types of service, such as removing and reinstalling items in existing locations we try to ESTIMATE our time, but these are budget estimates only, not quotes. Customers who can identify a minor problem, like a tripped CB or GFI are talked through the problem on the phone and then we send someone if they can't solve it themselves.
We charge a 1 hour minimum from our door to the completion of the job INCLUDING THE PAPERWORK. Then we charge by the 1/2 hour. We are straightforward with people about these charges and while we have the occasional no-pay like everyone, the company has been in business for 45 years and most of our customers are repeats.
