I agree more oversight is definitely an order, schools should have some kind of robust screening process in place to prevent taking in students who are obviously unable to pay it back. Especially if they are signing people up for degress that have few job prospects. Investigations into schools found to have high default rates would be a good idea I feel, find out the root of the issues.
Honestly I think most governments are missing a golden opportunity when it comes to post-secondary loans. What they should do is pay for large amounts of the costs for professions/studies that are actually needed. Like paying for a large chunk of the costs for people to become doctors for example, since doctors are pretty much always in need. It's better to incentivize people to get a useful education rather than punishing those who get a less useful one.