If you bought this book used, it should have cost $129:
http://titles.mcmaster.ca/text/detai...780 495011668
However, the one listed for 1A03 includes the 2 pin codes & 2 solutions manuals...I have no idea if these are necessary, but if they are, you might want to just return the book you bought and buy these...the only problem being, they are only available from Titles as new books, not used. I have no idea if you
need the pin codes, but it's something to keep in mind while you're sorting this out. You were told that it's the right book for 1A03 because I'm pretty sure they're the same
book, but it's pretty easy for someone to tell you you have the right book without knowing about all of the other stuff--and really, that isn't the employee's fault, since it's your responsibility to know what books you need. However, instead of getting them to refund you the difference, if possible, you might want to wait until classes start (or email the prof) and see if you need the pin codes...that way you can just return the book and get refunded the full $171 or whatever it was, and buy the other one, if you do.
I hope that made sense :S I've had a long day so my communication skills are kind of failing me