As promised, an update following my request to our hosting provider.
They manually edited the php.ini file to increase the upload_max_filesize and I've been able to the updates using Upload Package.
CPanel seems to have been showing the wrong values (file?) for the Home Directory file (it's a MultiPHP environment) for our domain.
I'll try to Install from Web next time I update, but I still want to thank you both for all your efforts even though I fell back on the method with which I am most comfortable.
Regards and thanks.