Incorrect estimation of a user story in sprint backlog

Hello, During our sprint planning session we estimated the user stories and created the sprint backlog. Later, we started with the sprint. While the sprint was executing, the DT realised that one of the story was estimated incorrectly - it should have been estimated at 150 while it was erroneously estimated at 100. What should the DT do now? Thanks for your help.

Posted By - Chaitali