When did you go?
I haven't been in two years, though my parents have gone more recently. The only thing I can think to comment on is a "taming" of the menu - I check it online from time to time and there seem to be fewer "exciting" or "adventurous" options than I seem to recall from the past.
That said, a lot of the menu changes daily, so maybe there's something interesting going on there.
Stet: It's not all that unusual for Blacktree to have very slow services. It's a small place and I have had dinners there with just one other table seated. It is highly unlikely that any professional establishment would inconvenience a party that way on purpose.
3029 New St, Burlington, ON L7N, CA
My sister and mother tried to go last Thursday when they were in Burlington. They made a reservation in person for the same day, about four hours ahead. When they returned, the host told them the chef had hurt his head or was sick and couldn't cook, so there would be no dinner service that evening. Nobody else was around, and my sister's boyfriend suggested that maybe they just cancelled dinner service because they only had the one table booked.
i've dined there on many occasions, when the place has been full and/or sparsely occupied. I've gotten to know the chef (Matteo) quite well. I cannot fathom for a minute that he would do what you've suggested. A restaurant lives and dies by goodwill and word of mouth. An action like that would be the kiss of death. I guess your folly was making a reservation in person. Had you booked over the phone, your telephone number would be known and you would have been called. Don't give up on this place. If you do you will be passing up a great dining experience. It truly ranks as one of my favourites on Ontario.