*****ulent SIM swaps to ***** air time from my bank

Uncontrolled SIM swaps and no protection ... I have had my simcard swapped 3 times this year, despite being put on watch list. Airtime has been deducted from my bank account and is reflected on my phone after recovering my number. After 24 hours the additional airtime disappears. The people at the MTN branch are unable to help in stopping this, nor do they understand how.