MTN gave away my oldest phone number without any notice!

MTN just decided that they are giving away my cellphone number that I've had since day 1 (plus minus 20 years), the number I use for my daughter's WhatsApp, the number I've got set up for password recovery, and of which I'm a registered MTN Easi Recharge customer. Not even a phone call! NO WONDER THERE'S SO MUCH ***** AND IDENTITY THEFT HAPPENING!

VERY UNPROFESSIONAL.