Ok! Now we know your career path is 100% business & finance. Now, are you saying you cannot be admitted into a certification program because of your IELTS score? Did you graduate from a canadian university or outside canada? If you graduated outside Canada then you will have to present better scores to prove your proficiency in the language. If you graduated from a canadian univeristy they really shouldn't ask for ielts scores again.
Regardless, there is no sense at all in you applying for a diploma or graduate certificate if you have an MBA. Like I said earlier, unless it's in an area totally outside the scope of an MBA. Perhaps you should share with us on the following:
1. Where are you currently located?
2. If outside Canada, is your studying a means to entering the country?
I just want to understand in order to give you the best advice I can.