About the permissions, as i was wrote the server is dedicated and access it through Remote desktop panel and plesk panel.. (Windows.. )
EDIT: Sorry for the edit, I hit the wrong button... the correct message follows on after this... Ken.
Someone with server experience may have a different answer, but AFAIK that should not make any difference. The hosting company should be able to assign ownership of the files to you so that you can make edits and install/delete files to your site.
As it happens my file ownership on my site has gone away while we've been working this thread, so now I must send a note to my host and ask him to run the code routine on the server that will reassign those rights to me. You may need to do that same with the person/people who run your server.