simulation using excel

I have to simulate bank transactions using excel. I've generated random numbers for the service time as well as the arrival time. The customer chooses the available server upon arrival. If all servers are occupied, the customer will wait in the shortest queue. Otherwise, if more than one server is available upon arrival, the customer chooses server 1 by default, then 2 and so on. The shortest queue is the earliest time of departure of the customer currently served by the servers. What would be the syntax for choosing which server the customer should go to? I have attached the file. please help.