More than the study permit I would advise you to think through what a certificate do for you at this stage of your career. If you are from India, it's unlikely a certificate is going to help you land a job given how these things work. Moreover if that is really your aim, a similar course in your country can do the trick for a fraction of the cost. I am sorry if it sounds too direct but sharing my thoughts as a fellow professional.
But if it's eventual immigration that you have on your mind, explore any degree/diploma not less than two years in duration, which will fetch you a three year PGWP. You say that your open school batchelor degree is not eligible for a master's, I am not sure that is necessary true for all systems overseas. Do check out public universities and shortlist a few and check if you could be eligible