The joys of the Volkswagen Caddy Natural Gas car

So I do own a car (contrary to what most people expect). About a year ago, I bought a VW Caddy EcoFuel. It runs on natural gas in normal mode and only uses the gasoline tank for starting (and when the natural gas has run out).

Up until 4 weeks or so ago I was pretty happy with it, but one morning, the car refused to start unless I hit the gas heavily while starting. I brought the car to the repair shop that belongs to the same place where I bought the car. After a few days of tinkering, they told me that

1. The particular car I own doesn't lock the tank when the rest of the car is locked and
2. Somebody poured an unidentifiable liquid into my tank causing the problems
3. Because this is not a problem with the car itself, warranty doesn't cover it
4. Removing the tank and the fuel pump and cleaning everything is going to cost 1200 EU

I am somewhat annoyed by some punk pouring an unidentifiable liquid into my tank and agree to pay the money. I also ask for the shop to retain a sample of the tank contents so I can at least find out what was poured into the tank, and perhaps get money back from my insurance.

They agree. When I come to pick up the car, the guys at the shop for some bizarre reason cannot find the sample. I sit and wait for ~1 hour, and they finally produce an unlabelled can from somewhere. Ok. I ask them to sign a piece of paper certifying that this sample is coming from my tank, and they tell me they will send it to me via regular mail the next day. So far so good.

So two weeks pass, and I call back 3 times for that piece of paper. At the beginning of the third week, I have to take my guinea pigs to the vet in the morning (yes, I don't only own a car, I also have guinea pigs). On my way back from the vet, the natural gas runs out, and the car switches to gasoline mode -- while I am going about 130km/h with a large truck behind me. The only complication: My engine switches off. Awesome.

So I manage to stop the car safely on the side of the autobahn and get towed to the next Volkswagen shop. About 2 hours after I leave my car there, I get a call from the repair guy there, telling me that they can see in the VW database which repairs were done on my car recently, but from what they can tell, these repairs never happened. They call in an expert that is certified to appear in court to take pictures & write a report, and he also confirms: The tank was never removed, the gasoline pump never replaced, and the 1200 EU were apparently charged without any of the stuff ever happening.

Clearly, I am somewhat surprised. To my dismay, I am also told that the actual repairs will cost about 2000 EU, and that there is still unidentified stuff in my tank.

So all in all, I am currently stuck with

1. 1200 EU for repairs that never happened
2. 2000 EU for repairs that are happening now
3. 2 * 300 EU for chemical analysis of the two samples taken
4. unspecified legal costs (most likely covered by my insurance) to deal with the situation

All in all, I am quite dissatisfied with VW on this front -- IMO they should've warned me that the tank doesn't lock, and they shouldn't have "VW Certified Repair Shops" that appear to attempt to defraud customers. I have trouble imagining that not actually performing the repairs was an "honest mistake" (although I usually live by the motto that "one should not attribute anything to malice that can be attributed to incompetence").

Anyhow, let's see how this plays out. As if I don't have other stuff to do.