Moving Large Sites From One Host To Another

I have to move some large websites from one host to another. The websites contain data about 1 - 3 GB, and my internet connection here is not that fast, so that downloading and uploading would take many hours. Unfortunately I have no SSH-Access to both accounts (old and new one), so I have to make it by FTP.

So I tried to make a tar file and moved it from the old to the new host. I made a tar archive of the whole webfolder (I used php to execute the shell commmands) and moved it by ftp to the new host. But now I´ve got troubles when extracting the archive on the new host: the extracted files are obviously created by the wrong user, so I can´t delete or access them by ftp.

So I´m trying to find other solutions to fix these problems. Maybe someone else had the same problems and could give me advice how to move large sites? Or do you know php-applications that can directly connect one host accout to another via ftp?