I suspect the csv file has been saved from Excel as a csv file, so Excel has already mangled it.
What version of Excel are you using?
You could record a macro of you using the Text Import wizard, where you'll be able to choose the 5 columns you want to import as well as ensure that the account numbers are imported as text and convert the date columns to real dates. Then it'll be a matter of tweaking the recorded macro for more general use.
If you have Get & Transform Data (Power Query) which is built in to the more recent versions of Excel you'll be able extract, transform and load your data exactly as you want it.