public IEnumerable <CallQueueCustomer> GetCallQueueCustomers(long callQueueId, decimal amount, int days)
        {
            var eventIdcustomerIdPairs = _eventCustomerRepository.GetCustomersForUpsellCallQueue(amount, days);

            if (eventIdcustomerIdPairs == null || !eventIdcustomerIdPairs.Any())
            {
                return(null);
            }

            var callQueueCustomerList = new List <CallQueueCustomer>();

            foreach (var eventIdcustomerIdPair in eventIdcustomerIdPairs)
            {
                callQueueCustomerList.Add(new CallQueueCustomer {
                    CallQueueId = callQueueId, CustomerId = eventIdcustomerIdPair.SecondValue, EventId = eventIdcustomerIdPair.FirstValue
                });
            }

            return(callQueueCustomerList);
        }