Repeated Successful instalations of Insider Preview 18290.1000 (rs_prerelease)

On the 3rd of December, 2018 I was forced to install Windows 10 Insider Preview 18290.1000 (rs_prerelease) and it was Successful. It then Successfully installed again on ‎‎Dec 8th and is doing it today, Dec 13th . This repeated full UpDate/UpGrade has consumed over 16 GB of my Internet's Data, in the last 2 weeks. Can anyone tell me Why and How to Stop It.