1. Log on to our client area. You can reach clent area from the following url
https://lankanhost.com/account
2. Click on Domains -> My Domains link
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3. Find the domain that you want to modify contact details, Click "Active" Button infront of the domains.
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4. Click on Managege --> 'Contact Information'
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NOTE: It takes up to 48 hours to appear these changes in public whois databse.