Thanks again. You have a point of view. I'm thinking right now to make a letter (registered mail) to them. Perhaps they will realize how difficult for me to take the risk of exiting Canada just to attend for my interview..If I`m not sure they will grant even a single entry visa in order for me to come back here in Canada..
Good luck. Make sure you state , you are here in-country with legal status, and residing in Canada (provide your address in Canada) and you are seeking clarification,
- on the reason for an interview,
- and on the need for you to go to Detroit for this interview as this requires you to get an entry visa to the US,
- and explain that it is your intent is to go immediately back to Canada after the interview and thus you will need a re-entry visa to be issued to you before going to Detroit. And attach the email sent to you instructing you to go to an an interview to be done in Detroit, for their reference. Also you could ask them - should the interview be required still- that this interview be done at a CIC office near where you are.
There must be something crossed in the processing of your application somewhere - it does not hurt to clarify why.
/God bless and all the best to you...