How to tell service workers that they made a mistake?

Hello,

There is a situation. I have repaired my car in the service. I costed me 180 eur. They did not finish to repair fully, I was still getting errors in my car.

They said to come back after 2 week, because most of them were on holidays that time. Plus they said I need to go to another service to change one sensor, because if I don't, then the engine might overheat.

I went to another service lets call it B, where I often go. They said the first service, lets call it service A - they are bad and telling nonsense. The engine cannot overheat because of this sensor not working. Plus they said the A service programmed in bad way the car computer, so there are still errors. And then they said they will take a look what can they do. I asked - how much will it cost, but they just said they need to take a look first, they will call me.

They did not call to tell how much it will cost and reprogrammed the computer and took from me 100 eur. Now I am not sure if they have done it good or not, couple of time I was still seeing the error and the engine power was reduced, as service mode as I understand, but after that it dissapeared and is not showing maybe couple of weeks. And also they said - if I get the error again, I should go to them and they will take a look.

So I have now spent 280 instead of 180. Which is big money. For example for you to have idea, in my country at city center I can eat lunch for 5-6 eur.

So now I want to tell to service A to at least repay 100 eur. They have done another physical, non programing repair also, but that maybe would cost like 20 eur or so, I think the engine programming costs the most.

If I go and ask them to repay, they might tell me that they do not have to repay, if I was still getting errors, I had to drive to them so they fix them. Its not their problem that another service took from me 100 eur.
If they were not able to fix after trying, then its more likely that they would repay.

I think its fault of service B that they were doing thing without telling in advance how much will it cost. I would have said, lets do not do it, first I go to service A, let them try or ask my money back.

But I am not able to do anything against service B, I do not want to get in the wars, because its likely not the last time I go to them still. THere is lack of services with reasonable pricings and nice talking people, and who I can trust that at least they will fix my car.

I am planning to ask nicely like:

"Hello, I was in another service to replace the sensor because you told me. That service told that you programmed it wrong and because of that there were still errors. And that service told that engine will not overheat because of non working sensor. And that sensor is expensive - new one might cost 180 eur. They fixed your mistake, but now instead of 180 eur, it costed me in total 280 eur for same repair. Could you repay me back 100 eur? "

Another option would be - tell everything same, but additionally tell - if you do not pay me back, I will tell in all forums wherever I can that story how bad you fixed my car. But I believe that is not an option. At least not at the beggining.

Do you think I can improve somehow the letter?