Unsatisfactory Boiler Maintenance by Bosch Repairmen

I live in Yalım neighborhood in the Artuklu district of Mardin. My address is Block Ka** Ke**, Apartment **. I got my boiler serviced at your authorized service center on Artuklu Ravza Street on August 16, 2023. The service cost me 450 Turkish Lira. But they didn't give me a receipt for the maintenance fee. I want to complain about the maintenance done on my boiler. The service was done carelessly. For example, to check if there is limescale in the boiler's honeycomb charger section, you need to follow a specific procedure. This involves pouring water into all four openings and rinsing them thoroughly. I'm confused why they didn't clean the parts during maintenance. I had maintenance done by the same service in 2021, and that time they did a more thorough job. I was happy with the results at that time. Unfortunately, the maintenance that was done in 2023 didn't live up to what I was hoping for. I'm writing this complaint about your service, and it has made me think twice about buying Bosch products in the future. I hope they listen to my concerns because this experience has made me think about whether I want to continue doing business with Bosch.