There are certainly errors that happen in Scarborough. I never got a notice to write the test from them, so I called ahead to the call centre and learned where I had to go. There was one other person there on the day I took said test, that didn't get a notice, either. I can't speak of other days where mistakes may happen, but if my experience was any indication, it is possible that they may have misplaced a few people's files, for sure. The Scarborough CIC office is indeed a really busy place when I was there, so I can understand how things may happen.
The funny thing about my test experience was right after I took the test. I was waiting in the next room for my citizenship interview, when I was called back into the testing room, and was told that I didn't even have to write the test, because I was 55 and over. That was the funny part, because I'm only 42. Clearly, the guy was quite embarrassed when I pointed that out, and he said not to worry. First time I was ever accused of being too old for something. ;D