Sales channels (salesperson/website) are types of intermediates. These can provide a valuable service provided these relationships are properly managed. If we look at marketing as being based on the 4Ps - product, price, place, and promotion - then utilization of a sales channel ostensibly improves your product placement by giving you access your business would not otherwise be able to achieve on its own.
Think of Amazon.com or eBay. Millions of potential customers and 24 hour access to them. The upside is tremendous, but there is something to watch out for - pricing. If the channel marks up your prices in a noticeable way and pushes it outside of the price point where customers are comfortable you will start to lose sales. There must be synergy between your pricing and the price they propose to the customer. If you have no control over the channel's pricing then it may be more beneficial to establish your own means to access the market.
A local restaurant opens up and uses a third party delivery service with its own website to handle deliveries. The service, however, presents a higher price for all menu items. The dollar per item difference makes them less competitive than nearby competition when customers recognize the price difference on the attached menu that comes with their order.
The near ubiquitous presence of the Internet has changed customer expectations regarding engagement.
The original sales cycle involved sales professionals interacting with unfamiliar leads, quickly using buying signal matrices to qualify them, and following up with canned presentations that largely missed the mark.
Today customers require three things: engagement, education, and subsequent buying assistance. What was once viewed as a buying signal is now more often a request for further engagement and education, making the sales process more of a mapping between individual client needs and products/services.
Customers are increasingly viewing transactions as occuring between people that are supported by a company. You'll see this in how customers tend to look for the same sales or service individual rather than go through regular channels. Transition to a different role or region nowadays should involve an introduction to whatever resource is taking your place. If that is not possible then at least the new resource should know who the old one was and what customers liked about him or her.