The only solution is to figure out which keywords they're bidding on and outbid them. Only 170 people search for that domain each month. You probably already have near 100% click through on it. Is it worth the trouble?
Most people click ads frequently.
Many (most) people don't even differentiate between ads and organic results.
People often enter web site URL into search box.
According to Google keywords tool that you probably used, there were 170 searches for postjobfree.com and 91 search for www.postjobfree.com
I guess it's not too many to worry. But there is also postjobfree with 2900 searches. These are users who are searching for my web site specifically.
That does worth the trouble.
While on phone call (inbound!) I experienced that it's hard to explain to users how to find my web site on Google. User enters the term, but then first 3 results are competitors' ads...
You are probably right that the solution is to outbid competitors for my terms. I hope it wouldn't be too hard to do, considering that my ad should have high click-through-rate.
I'm going by my own results with AdWords, not by faulty intuition.
> While on phone call (inbound!) I experienced that it's hard to explain to users how to find my web site on Google. User enters the term, but then first 3 results are competitors' ads...
You might try putting "official" somewhere in the meta description to see if that helps with the confusion. Your site seems to be what people are looking for, so a simple change like that will tell people "this is the one you're looking for."
edit: It doesn't look like you have any meta description. It's not usually needed, but I think it might be essential in this case.
But if you added it - would it be something like: "The art and writing of Michael Robinson (by Michael Robinson) - official"?