My mtn account was hacked

Went to an Mtn store to upgrade my account to my surprise I've told that I bought an iPhone 16 pro max on the 15 December 2024 in morning side my personal details were updated my address email address if this was done in the branch how did they verify as far as I know thus biometric system that was supposed to be used I mean I had my account over 12 years with them I need answers asap from mtn