If you can confirm with your bank that the money did come in via EFT then you should be safe as the normal procedure to reverse an amount that has "incorrectly" been transferred into your account is as follows:
- Person A transfers money into Person B's account via EFT.
- Person A discovers the amount went into wrong account ie wrong account number used etc.
- Person A contacts his bank [Bank A] to reverse.
- Bank A contacts Person B's bank [Bank B].
- Bank B contacts Person B to confirm that money was incorrectly transferred into his/her account.
- Only if Person B agrees then the amount is reversed.
So an EFT should not be reversible without you being a part of the loop.
A cheque on the other hand is reversible at any time at the option of the cheque issuer.