http request/response understanding

Question

hi
I have a client/server problem
I am using a soap mtom encoding service (basichttpbinding) and that service has a method that i request. It starts doing allot of work and after maybe 10-20 minutes i receive the response.
So, the problem i am having is that some times i don't get a response at all. If i let it, my client would wait for 5 hours before timing out.
The person that created the service is saying that the work has finished and the response should have been send to me and that it must be a network issue that i don't get a response. He is not seeing any errors in his logs.
I, on the other hand is not sure that it is a network issue. So i would like to determine if it could be a network issue.
My understanding of basichttpbinding is that it is connectionless, so i connect to the service and make a request and the connection is closed. Then i wait for the response until the timeout happens. The service connect to my client and send the response and closes the connection.
If i try to send a request to a service and the network is down or something else is wrong with the network, i think i will get an error from the underlaying communication layers. So when the service sends the response back, it too should get an error, if for some reason, it could not reach my client.
Is my understanding wrong? If so please correct me and also how can we exclude the network completely as the reason that i don't get the response.