Robert Bosch GmbH Bosch Service Employee Threathened Me Stuttgart Stuttgart

I have bought a combi broiler from Bosch in Turkey. It was supposed to have a free of charge installation, however the service employee said he needs to charge me 600 TRY (around 40 USD at that time) because he is going to install a room thermostat which wasn't bought from them (I bought it on-line seperately) even though it was expensive for me, I had to accept it. I paid the guy 600 TRY and he installed it. However I didn't have chance to try it for a couple of months because the weather was still warm. After I tried it a couple of months later, I noticed that they didn't install the thermostat correctly, so I had to call another guy to install it and than called the Bosch After Sales Service to ask for a refund for my 600 TRY. They told me that their employee should have charged me 150 TRY, because that's the price for installing a room thermostat. But they didn't it's clear that their employee ripped me off, but they didn't accept it. They asked for the receipt (which was written in handwritting), on the receipt it was written 600 TRY, but it was scratch and written 150 TRY on the side (attached). It obvious that the guy wrote 600 TRY there and got my signature and right before he handed me the receipt, he corssed it out and wrote 150 TRY.

When I claimed this they said they will take care of the situation and a couple of hours later that employee called me. They gave my number to him! He called me and said he only took 150 TRY from me and when I disagreed the started threatening me saying "I installed that broiler, I know where your house is" and he started describing my house in details to prove that he still remembers my house.

All I did was buying a broiler from Bosch and claiming the money that was stolen from me. Now I feel like I'm in danger. I will be out of town next week and I can't leave my wife at home, so I will send her to her parents. And Bosch is doing nothing about it, all they said was they contacted to Technical Service and they told them that he charged 150 TRY. That is not even the issue now. I don't even want that money back. They didn't understand that I am worried that they may hurt me so I had to file a complaint here.