public Payee AddPayee(Guid userId, Payee payee)
        {
            Payee res    = null;
            var   detail = _UserCollection.GetById(userId);

            if (detail != null)
            {
                var linkingBank = _LinkingBankCollection.GetById(payee.LinkingBankId);

                if (linkingBank != null)
                {
                    // get payee detail
                    var payeeDetail = _UserCollection.GetByAccountNumber(payee.AccountNumber);


                    if (payeeDetail != null)
                    {
                        if (string.IsNullOrEmpty(payee.MnemonicName))
                        {
                            payee.MnemonicName = payeeDetail.Name;
                        }
                        payee.Id = Guid.NewGuid();
                        var countModified = _UserCollection.AddPayee(userId, payee);
                        if (countModified > 0)
                        {
                            res = payee;
                        }
                    }
                }
            }

            return(res);
        }