Mutilpe Charges on Customer Account - Timeout Errors

My customer has multiple charges for registration on their account.

Multiple charges are probably the result of a connection "timeout" error. Timeout errors can happen for a number of reasons. The server, the requesting device, the network hardware and even an Internet connection can be at fault.
Timeout errors are difficult to explain. In short, the transmission of data from the customer's device to the servers and back to the customer is interrupted. Essentially, the device that made the initial request for data from another device "gives up" on waiting for that information to be sent when a timeout occurs.
In all likelihood, the errors are caused by the customer's modem trying to communicate with their Internet Service Provider (ISP) and not receiving a response. This will cause the modem to resend the information a preset number of times and eventually time out and terminate the connection. Unfortunately, our server then receives information for "multiple" orders and processes the orders as multiple orders in the customer account record or as incomplete "orphaned transactions" after the connection "timed-out". 
Orphaned transactions are only visible on our servers and are automatically reported to our "host' administrators. The transactions are usually completed within 24 hours of being reported and will then appear in the customer account record.
Below are a few more details about timeout errors:
Network Infrastructure Error
A request from a device has to pass through multiple checkpoints on its way to the server. If any of these checkpoints is too busy, the request may be dropped. For example, a request to load a website in a Web browser may time out when connecting through a home network because the router is overtaxed with requests from other computers and devices on the network for other servers.
Network Hardware Error
A server request may time out because it was blocked from ever leaving the computer or network and never got to the server. Firewall and router port blocking settings can prevent outgoing requests to servers. Reconfiguring the Firewall or router to allow the request to pass will fix the problem.
Data Request Error
It's possible that the server suffers an error pulling up the requested data and is unable to send anything back to the computer. When this occurs, the request makes it to the server, but the server gives up and never sends anything back. Data request errors can be resolved by sending the request again.
Hopefully, this helps explain the cause of the multiple charges. Fortunately, timeout errors are actually pretty rare within our system. If your site seems to experience an uncommon number of errors, this may be indicative of an ISP issue in your area. Unfortunately, the exact cause is very difficult to determine.