You need to change your study permit, not simple like writing a letter to the government.
You can talk to the international advisor at the university of Ottawa. He will tell you more details.
ISA is Mr.Abdo G. Ghie', he is in vocation back in Arbic...his office in located in 538 King Edaward Ave. International Office. But I don't think ya need ISA though, there is a very nice lady in the front desk who can help you w/h everything! Good luck!