Applicants seem to overestimate the importance of one's passport when it comes to admissions.
If you're Greek but you've lived most of your life in Australia (you went to school there and work there), you'll be considered basically an Australian.
Nationality alone isn't what matters. Otherwise, every single applicant from Chad, Madagascar, and Bhutan will be admitted every year even if they were goat herders and shepherds.
Ultimately, it's about your professional experience. If you worked in a corporate job at a big company (like Telstra), your candidacy is more similar to folks who worked at say GE, O2, Siemens, etc. no matter which country they're from (or what part of the industrialized world they're from) because the nature of the job responsibilities are going to be similar.
What will be more of a concern is why you still want to go back for yet another related degree (MBA) after having gotten not just one, but two business degrees (BBA and a Master of Commerce). Aren't you sick of school already? Sooner or later, you have to stop going to school each time you want to switch jobs. As you hopefully know (or will know with time) - in business, it's still ultimately about real world experience. Collecting degrees can actually create more negative impressions for recruiters who may believe that you are too academic and not pragmatic/street smart enough.
Sounds like you have the start to a solid professional career, working at a large respected telecom. Focus on that for a few years, and then go from there. You probably won't feel the need to go back for another degree.
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