How can I get all my papers under the same Scopus profile?
As Federico indicates, the contact form (“Ask a question”) has a field for suggesting correction to the index:

     

You can directly send them the papers in question:


  Please attach a copy of the missing or incorrect document, this is essential for us to verify the changes and make the corrections.


While I don't have any direct experience with Scopus in that area, they are generally serious and I think they will act on your request. I have once contact another index provider (Web of Science) with a correction, and they updated the data within a week.