Really sorry to know your unfortunate situation. Based on your original information I have drawn a few conjectures, I hope the following pointers can provide some reliefs:
(1) Stephen Guest and his assistance were not able to protect your interest (sale contract, including your deposit). You can gather all the evidences against him ( all legal documentations, i.e. anything that has his lawyer stamp and signature + all deficiencies that you mention). This damaging information can provide a good bargaining position against him when submitted to the LAW SOCIETY OF CANADA.
(2) The sale representative was misleading you; furthermore he was evasive when confronted with obvious contractual misrepresentation. Gather all associated information and use this as bargaining chip when submitting to Real Estate Association of Ontario.
Even if you have done the above 2 items, you may not get any monetary return from Minto. Apparently, Minto was taking advantage of the above missteps and just took the money.
(3) if you can get your story out to TORONTO media ( chinese and english newspaper/radio) and get some public sympathy, Minto's name will be at stake in Toronto. Toronto is a bigger market. I think they will be more helpful with media exposure.
Please be aware, you need to be very careful when discuss this issue; always use facts and figure, including photocopy of the original documents , so to avoid defamation lawsuit.
Good luck!