Nadya,
I would definately go with some kind of Excel automation. However, before proceeding, you should nail down the provider of these files to be consistant in what they give you. Get everything in writing and go to their supervisor if you have to. Many is the time I had to fix a text file from a client because they couldn't decide what kind and what format to send. Get them to commit before they give you anything.
HTH,
Winn Pauley