I have done graduation in India and had taken post graduate diploma. Even when I mailed clg about this they said they have students with the same past studies as I have done.Are your studies also showing career progression means you are not doing post secondary diploma after an undergrad degree.
Also did you submitted SOP explaining future prospects with your academic marksheets?
Best way to know why you got a refusal is to apply for CAIPS notes. Search the forum on how to do it.
Do I need to attach marksheets with SOP?? m not aware about this