It's crazy how they give any reason. What transcript did you submit this time? Same as the last time or did the University/you figure out what the error was?
Definitely update your SIN. TRV should be done as a back up - in case you need to leave the country urgently. You can do it now or next year, whenever you want.
I believe you need the hard copy, which apparently has more information in it. The authorities apparently need the same to stamp your TRV. I could be wrong.