If you are looking at having a website designed then you have a choice of who to use. You can opt to use a self employed / individual to design the website or you may wish to go to a design agency.
There are pros and cons for both, but using a design agency does seem to have many more advantages.
With an agency you have the peace of mind that they will probably have more than one designer, meaning if for example, your designer goes off ill or on holiday, there is someone else to cover the work. Also as the saying goes, two heads are better than one, or in the case of an agency often tens to hundreds of heads. Allowing people of all experiences within the design industry to get their heads together to come up with a design that not only looks good but works and allows for growth is vital and an agency will have the relevant people to do this.