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they won't allow you to upgrade phpmyadmin? jesus!
then the other way to do it if you HAVE to stay with your webhost is to save the Excel file as a .csv and then email it to your webhost and ask them to import it into mysql via the command line
if they provide you access maybe you can ssh it via the command line yourself
if they wont do it then you know it REALLY is time to find a new webhost!
Take a look at this thread from our library
Basics of extracting data from CSV files [webmasterworld.com]
the steps laid out in message 2 would work. For step 4 just construct your insert query and then in step 5 issue that insert statement to mysql.
everything else is the same