Our experience with data retention and the right to erasure largely arose as a result of our complaint against a children's website and the company's absolute refusal to remove personal information. We did get contacted by former members of that social network, once we brought the complaint. We had a number of them call us and say that they had this problem with the site, and yes, that it was a difficulty.
Occasionally, a person will email us and say that they don't like the privacy policy of company X or Y and can that company really do this or that. So, yes, we do have some contact with people, but on this particular issue it was more after we raised it that people said they didn't know how to get their information erased, and could they?
The answer, unfortunately, at the moment is no, they can't. Although the Privacy Commissioner did say in that case at the end that they would like the site to remove the information. That was the first time I ever saw it. Nexopia waffled on that. They subsequently sold themselves to other owners, who promised to remove it. I'm not sure if it's been done.