Mtn gave my number to someone else!!

I'm writing as a very irate and disappointed customer. I've had my Mtn prepaid number for many years, I've even lost count of the number of years. I do buy airtime and make calls and even use Mtn Momo as well to recharge.To my surprise 6 days ago the number was suddenly out of service and I thought it was a network issue. The last outgoing call was in April, meaning my phone had airtime. On Friday I then decided to call MTN because of this inconvenience. The lady I spoke to said my number needs to activated🤔 I asked her to explain to someone who doesn't understand the word. She just said "yes the number needs to be activated", that all. This sounded like a number that has never been used... I then asked her to pull records for me and she kept saying the number is not showing as it needs to be activated 😞 I then asked if this then means that my number never existed? She couldn't answer but promised to activate my number in 24/48 hours. Monday (today) my number was still not working and I went to Mtn in Gateway Mall and the lady said I must wait 24 hrs and come back. Today I went and my number is given to someone. When I called someone picked up a a call. This number I use for my banking. How is this possible. Why did they take my number without any warning. This person is receiving my calls why MTN did this to me after all these years of being loyal to them?