I am working as a technical support manager and when the customer has some problems, it takes much time and efforts to find out the core of it.
Please advise any service that can help our technical guys to manage and operate with the customers remote PC and to resolve the issue much faster. The work should be done strictly through Internet, without any software installations.

This is an older topic and you have probably solved your issue.

If the client is running Windows XP or better you can remote desktop into their computer to diagnose issues. This requires no installation and is fairly easy to set up.