problem regarding expiry date of RENEWED study permit

I am an intertnational student in Montreal, Canada and I have abit of problem regarding my RENEWED study permit expiry date.
This year, both my CAQ(required for studying in quebec) and study permit were expiring on 1st August 2009. Intially, I applied for CAQ renewal in April 2009, and I was given a CAQ till 31st March 2011. Since I was planning to leave the country from June-August, I hurridely renewed my study permit quickly in May 2009, (as it would have taken a longer if I renewed it outside of Canada) and thus my study permit was extended till 31st March 2011.

The only problem is that I finish my studies on 30th April 2011 and the last month month is not covered by either of the documents. So i contacted Immigration Quebec, and it turns out that they had misinterpreted and errored in their assessment. Consequently, they issued me a new CAQ that is valid till 31st August 2011, without any additional cost.

However, when i contacted Immigration Canada (their call centre) about the expiry date for my study permit, I was told that since I have a new CAQ, I have to reapply (and thus pay $150) for another study permit.
This is seems kind of ridiculous given that I am forced to pay $150 for a mistake made by Immigration Quebec. Plus, the current study permit falls short of one month (i.e. April 2011) to allow me to continue my studies. My only fault is that I should have had contacted Immigration Quebec about the expiry date before I applied for a study permit.

IS there is any way for me to have the expiry date changed without having to pay an additional $150. Would this mean taking up (potentially expensive) legal course? I would really appreciate any useful suggestions.