Random Data missing when Importing contacts from excel to outlook (2003)

I have to sort out a huge base of about 2500 contacts infortunatelly in excel

The data is entered in a sloppy way ... you got writen comments next to mobile numbers, mixed Greek and English languages, full text Addresses (Not separated in Street, Region, Country etc), and any other stupidity you can immagine.

Nevertheless I managed to import this mess on to Outlook 2003 (the standard way - put headers in the excell according to Outlook requirements (LastName, FirstName etc) selected the data area (all data columns) and inserted a name for it. When mapping fields in the outlook import interface I decided to map the full text addresses column as Notes (full text supported)

All went fine (after several tries though) and imported this huge list of contacts.

THE PROBLEM: there is data missing randomly in over 50% of the contacts.
Some Contacts are without "BusinessPhone" numbers, others without MobilePhone and so on...

I cant figure out what is going on since every time I import the Contacts (tried many times to find some paterns) there seem to be different data missing ... even though Greek fonts (that I feared would be an issue)
are imported properly (Unicode Supported)

Could it be that the Outlook refuses to import some data because the formating in the excel sheet does not correspond to what it expects to receive ?

Is there any particular formating that has to be applied to the ecxel sheet or cells for the data to be properly imported?

Any ideas on what might be causing this weird behaviour?