Hi Sean,I deleted your post from the forum because it contains sensitive information (clientCustomerId, developerToken and userAgent). Please refer to these guidelines before posting in the public forum.The UNEXPECTED_INTERNAL_API_ERROR could be triggered by a temporary server-side issue. Having said that, I tried to execute the CampaignExtensionSettingService against my test account with similar setup based from your SOAP logs and was able to successfully add Callout and Sitelink extensions on my end. Could you try to execute the same API request and see if the error persists?Regards,IvanAdWords API Team