Indima SPRL - a garage to avoid

Here's a story to let you think over before ever considering leaving your car there. The garage is located on rue du Prevot 33, 1050 Ixelles - it's one of the very few garages close to the Chatelain/Bailli area - a quarter popular with expatriates who, if own a car, sooner or later start looking a garage for themselves in the vicinity.
I brought my car there with two clear symptoms - unstable revs when idling and a noisy bearing. Left the car in the morning, got a call in the evening it was ready and I owed 640 eur. Alright, somewhat pricey, but ok, let's go and see. So, what they've done is changed the bearing - good, the belt (they had found a crack) - good, changed the air mass meter (debimetre in French). The meter cost 300 eur, changing it was 5 minutes, so I think all the labour (2 hours) went into changing the bearing. Also, a 80 eur charge for computer analysis. And the car still has the same problem. Great! So, what they've done is - put a computer to the car, found the first glitch and thought - this must be it. What is it, 300 eur, let's change it. Does it help? Oh well, he's got a new piece at least. FOR 300 EUR ON A 15 YEAR OLD CAR. Should we think twice, before doing it? Should we call the client for confirmation? No, let's just change it and see how it works. Also, why not change the vipers for another 50, he'll be pleased.
There I am, trying to make sense of the bill, and saying that I cannot pay a total of 640 eur for a changed bearing. Alright, they will look at it, I should leave the car. I leave the car.
With half a day past, I call them to ask about progress, they say something I do not fully understand, but the message is - we're working on it. I look the word they mentioned up and understand they cannot start the car. This is my fault, by accident I have activated the key which prevents starting the car. When the ignition is turned, nothing happens - no lights go on and the starter doesn't even engage. I hurry to them to set it straight. I find the two men having disassembled half of my car looking why it wouldn't start. Look, I've had these situation with other repairmen - always, they call me to ask if there's any secret switch. These guys, faced with suddenly no ignition lights coming on, think, right, we've got some job to do here, let's repair. Again, no calling to the client, no thinking twice of what the problem might be, they just start to disassemble the car. Later they're even telling me they thought it was fuel, so they added some liters or something. No ignition, no starter engaging and they think it's fuel.
Ultimately, they say they've found a leak in a tube and stabilized the revs, I take the car and leave frustrated. When I ask for my old air mass meter, they claim they've given it in exchange for the new one (like with alternator), I wonder what the manufacturer would do with that plastic sanitation tube which has no value apart from it's electronics. I was left unsure whether there was any problem with the meter at all. Also, found out in another shop they had charged me 35 eur more on the meter, I supposed in some proportion this applies to the rest of the parts as well. Plus, the vipers - who in the world asked them to change vipers costing 50 eur?
It's hard to tell apart the parts where they were ripping me off and where they were being incompetent, or rather, dumb. A strange and devastating combination - a dishonest and stupid repairman. They're hourly rates where of the higher end, so it's not like they're giving discounts for their lack of competence.