It is not necessary that one who can design can also code with same proficiency. This is the case with most of the freelancers
and web designers. Some times their work load don't let them try their hand in coding and rest of the time they back out after wondering the size of the codes.
I have had the same kind of experience in past and then I reached to http://xhtml.
pixelcrayons.com. Since then all my work regarding codes is handled by them. They produce satisfying work and committed to their 100% satisfaction guarantee promise.