Hi Ginbee,
I completed my Masters thesis after an upgrade type PG Cert and also did two Masters course work units before the thesis, so that now when I do apply for a doctorate (in a while-having a breather for a few months) my referees will be fairly current. However, my former partner was an associate professor and often was approached by exstudents for these sorts of things. Sometimes the time gap did make it a bit difficult for him to comment effectively though. He tended to be a bit reluctant to comment after around a 10 year gap. However, have you thought of approaching your old lecturers anyway and possibly finding a contemporary back up- maybe a professional referee who is more current- as well? It might help with the time lapse from the University's perspective.
The other thing is that possibly the University might want you to do a course unit or two just to make sure that things are fine...which sounds really annoying. It certainly put me off at first, but I finally accepted that I had to do this and now of course have no regrets at all. But I was pretty p$$$d off at the time, I remember.