Hi, My profile is almost same. Instead, I have 6.5 bands not less than 6.0 in each module in IELTS. I have chosen a post graduate course Supply Chain Management Course. 2-year mechanical engineering technician diploma which you are talking about is a graduate diploma ( which everyone can choose after 12th class ). You must choose a post graduate diploma or certification. If you will choose lower level education, then there will be high chances of visa rejection
You have three options, either go for Master's degree ( You have 5.5 bands in one or more than one modules. You might not be eligible for master programs in most of the university.) The second option is you can choose post graduate diploma or certification of one year or two in the mechanical field. The third option is you can choose a postgraduate course in management fields like project management or supply chain management.
Your SOP should be strong regarding your course selection! Good Luck!