The one about the sink

Ever since we moved into our small (but beautifully formed) house five years ago one of the sinks in the kitchen has been a bit dicky. We've had several plumbers come to fix it, each one slagging off the work of the one before and adding an extra pipe here and there, and none of them actually fixing the problem. What we've been left with is a sink which sometimes drains, sometimes not, sometimes smells, sometimes not and so much pipework it looks like the Madrid Metro system in the cupboard underneath. A couple of days ago it all came to a head when all the dirty water from the dishwasher erupted from the outlet pipe and flooded the kitchen. I'd had enough. It was time to get the big boys in. I contacted a company which specialises in unblocking drains and they came this morning.
"Oh dear, oh dear" said #1 when he opened the cupboard. "Looks to me like somebody's been trying to do the job of a professional here", he managed (cleverly I thought) to say whilst sucking his teeth. My heart sank. "Compressed air", he said, "that's what's needed here". "Compressed air", repeated #2. I stood back and watched them shoot compressed air down the main outlet. "That should do it", #1 said with a smile. "Should do it", echoed #2. I felt my eyebrows meet in the middle. "But how do you know it's worked", I asked. "Because it's compressed air", he said, "and that's what it does, it works". Then he got a pen out and I thought, "oh please, no, please don't draw me a picture!" But I was wrong, he started to write my bill.
This is the point in the spaghetti western that my home has turned into with all the cowboys wandering through it that I know I should make a stand, say my piece and refuse to pay. But the problem is I always think they must know what they're doing and certainly know more than I do. "You are going to put my plumbing tribute to the Madrid Metro system back aren't you?" - I said instead. "That's my colleague's department", slimed #1. "Work of art" said #2, "should see my plumbing..." I pushed that thought away and replaced it with a confident glimpse of future sink heaven, all draining and odourless after its treatment of compressed air.
They raided my wallet and left. Wanting to get everything back to normal I started putting the clutter back into the cupboard under the sink, and that's when I heard the drip.
Does anybody know a good plumber?