Get the users to email their service requests to a Sharepoint List. You can manage all user issues from there.
You can use views to set up a user view of issues so that it only filters on their own issues too, if you so wish.
Go in List Settings>Incoming Email Settings
Create a Service Request List and allow users to create new items. In the List Settings, restrict users so they can only view/edit their own items.
- Set all fields to 'required', to ensure you get all the info you need.
- Add some Choice fields (you can define some categories this way).
- Every time a new item is added it automatically has a Sharepoint List ID assigned to it, that can be your SR number.
- All users would need is a link to the SR List; add it to your intranet, they can add it to their browser favourites (or you just email them the link).