One of my puppy owners had an appointment to see him after they had returned their 10 month old pup to me for the second (and supposedly final) time and I persuaded them to take it, and I would take the dog up and meet them there.
He told them exactly the same as I had, but because he was a professional and they had to pay they believed him, took the dog back and he lived happily with them till his death a couple of years ago.
After that I went to spend the day with him and found it facinating, got roped in for all sorts of things and so did the bitch I had with me.
If he is still as down to earth and common sensical (is that a word?) as he was then, you should find it very useful.
Christine