reason - your proposed studies are not reasonable in light of one or more of your qualifications. previous studies , employment , level of establishments , language abilities , or your future prospects and plans.
First of all, I don't understand above reason which I've been seeing lately thrown out to many students hence confusing them about what exactly is the root cause. Does Immigration really care about your IELTS score despite the fact that you have acceptance letter? The college gave you admission based on IELTS so what's the point of rechecking IELTS for Visa. So, if you have 6 bands overall and you meet the eligibility what's the point of beating around the bush?