Maybe better to implement actions as commands

[cemozudem]

For command pattern, I would prefer actions implemented as commands, In my opinion, using case/if else statements here defy the purpose of implementing command pattern...

So, instead of this:

        public enum Action
        {
            Deposit, Withdraw
        }

Maybe it's better to use this:

    public class DepositCommand : ICommand{ }
    public class WithdrawCommand : ICommand{}