ATM machine Dispenser

Hi folks,

Recently I received a letter from Maybank saying that my Maybank was overdrawn in one of their ATM machine amounting to RM 9K plus, they required me to return the amount overdrawn or else they will not hessitate to take legal action against me.

Can anyone here tell me what should I do? Is it possible for them to sue me for the said amount?

Many thanks in advance.