Three ways by which you may be able to get your document attested:
1. Contact people who are in this line work. One company that probably does this type of work is Sheen Services. You can get their contact number through Google. Possibly, some typing centres may also be able to get this job done for you.
2. Go over to the Sharia Court located in the Coniche area. Usually, there is some lawyer hanging around there. You can also ask people working at the Court for guidance and you just may not need the services of an Advocate.
3. Go to Google and search for Advocates in Doha and it will provide you with a list of them. Keep in mind that they don't come cheap.
Lastly, in future if you like to post something at QL, just a single post may get you the assistance you seek. Posting the same thing three times makes no sense.