Debited my monthly debit order TWICE!

Yesterday i got a notification that MTN had debited my monthly debit order TWICE! Due to the lockdown, i only received half of my salary and budgeted that all my debit orders would just be enough for my salary paid. Now, MTN has taken of double the debited agreed monthly debit order and now i don't have enough to pay my other debtors! MTN please rectify this problem ASAP!