Are the marksheets from HK? Who needs the certified copies?
If the marksheets are from HK, your institution should be able to certify them for you.
As a last resort, you can call your local legco representative. Most of them are public notaries / JPs. Most district council reps are also JPs.
Take Wanchai for example...
http://www.districtcouncils.gov.hk/w...ember_info.htm
Why not find your own district council and call the members and see if they'll help you.
http://www.districtcouncils.gov.hk/front_e.html
Needless to say, any legal firm will do it for you. For a cost though. Many senior branch managers at banks also have notary powers.