Content ***** using my MTN number

I have suddenly been bombarded with sms' s confirming my subscription to different contents. I have never knowingly subscribed to any content. I contacted MTN customer care and was told by the very polite lady that I need to dial *141*5# daily and unsubscribe. She said that she had to do it daily as well and suggested that I do this too in order to stop being charged. Yesterday I cancelled about 7 content subscriptions and about 8 pending subscriptions . Today I again had to cancel about 7 subscriptions and about 3 pending subscriptions. I need MTN to explain how, when and who is making these subscriptions using my number. I also need MTN to permanatly prevent any subscriptions from being charged to my account... in other words block my number from receiving any subscriptions. Alternately I need you show me how I can take full control of this to prevent thus ********** activity. I trust that as my service provider you will take my concerns seriously enough to ensure a permanent solution to this serious matter.