CSV Download problem?

I downloaded a CSV file back in May and entered around 150 directory listings, which when imported was absolutely fine.
Now I have another few hundred listings I want to put in, i’ve downloaded another CSV to populate.
Now the CSV back in May was spanned across numerous columns and easy to populate, but the CSV i’ve just downloaded now has all column headers in cell A1, and all of the listings data just in Column A, seperated by comma’s, this is very different to the previous one I managed to download/re-import.

Whats going on and how do I get the original back?
Thanks