Changing of personal details without permission

<p>I recently needed a proof of address and when pulling my vodacom statement which was always on the correct address i found that this was changed back to a previous address from 7 years ago. I pulled past statements and somewhere in last 18 months they just changed it without my permission even though i phoned and they promised to fix this problem its still incorrect. How can a company jusy change personal details its unacceptable</p>