Why does a pdf file have strange characters in the text?

I downloaded a pdf file from an insurance website about a year ago without a problem. Using the same computer and browser (Safari) I have just downloaded the most current version of this pdf file and the first page or 2 appear normal but the many pages after that are illegible. Some of the text characters are OK but most look like they are in a (perhaps) foreign language font. The company sent me a copy of the file attached to an email that they say is legible on their end but it still has the same problems as before. I also tried to download it in Chrome and Firefox but it makes no difference. Is there a solution to this problem? Thank you.