/// <summary>
/// Attempts to edit specified BankAccount in the BankAccount collection.
/// Throws an ArgumentException if the account can not be found.
/// </summary>
/// <param name="ba">BankAccount to be edited</param>
/// <param name="surname">New surname</param>
/// <param name="accountNumber">New accoutnumber</param>
internal void EditBankAccount(BankAccount ba, string surname, int accountNumber)
{
if (ba != null)
{
ba.EditBankAccount(surname, accountNumber);
}
else
{
throw new ArgumentNullException("Bank account to edit not present.");
}
}