You know how important your customers are to you so let thme know too. Provide them with a login from your web site so they can log and track requests with you. They can keep you up to date of staff contact changes and why not let them know what you can offer them personally as well.
Colours, fonts and logo are configured as your own and you can personalise welcome text and embed images for each customer as well.
Shared Open source code ensures a total blend with your web site themes.