we have an old house with interesting plumbing issues; the downstairs bathroom sink was not draining; we tried to fix it ourselves and made it worse so that it drained too much
the plumber was understanding and even walked us through what we did wrong; he also had some fun trying to figure out the best way to help us as the previous owner glued and screwed in the sink and built the cabinets and counter around the sink so it couldn't be easily fixed by the plumber
if you can get this company to help (as they are very busy) it is well worth the money