importing a Yahoo csv file back to yahoo address book

I exported out my address book out of yahoo. Yahoo exported it out as a
yahoo_ab.csv file excel spread sheet.

When I went to upload the file back to yahoo address book it said it can
only take 2000 contacts at a time. My file from address book is a little over
5000 contacts.

I called Yahoo Support and they told me that I needed to breakdown the file
in to 2 000 contacts at a time. So we copied 2000 and pasted them into a new
spread sheet and saved it as a .csv file as they directed us to do.

When we uploaded to yahoo it said it is unrecognizeable file and
incompatable file.

Yahoo tried them selves to upload the files them selves with no success and
now they say its a microsoft issue. I find it strange that they choose to
export there contacts as a excel sheet .csv- but when you try to upload it
back in won't take it.

Please some help what can I do to make yahoo address book recognize the files.

Frustrated!

Thanks,