Viessmann Replaced My Boiler’s Main Board but Took the Faulty One Without Explanation

On 12.02.2025, our Viessmann boiler with serial number 7514912401447100 displayed an F5 fault, so we called the service center at 444 9092. They informed us that a service request had been created and that we would receive a call. On 13.02.2025, I contacted Çakmak Technical Services at 0212 660 07 76, and they said they would come during the day depending on service availability. The technician arrived and diagnosed a faulty main board, stating it needed to be replaced. They mentioned it could be repaired, but since it would not be done on the same day and considering the cold winter weather, we opted for a replacement. When we questioned the high cost, they said the main board was priced at around ₺8800. Out of necessity, we agreed, but after removing the faulty board, they insisted on taking it with them. We paid for the replacement, but when I asked why they were taking the defective part, they simply stated that this was the service’s policy. When I inquired if they were repairing these boards and installing them in other boilers, they denied it, saying it was a revised board, though I was not given a clear explanation of what that meant. I could not get an answer as to why they were taking the faulty board, so I called both Çakmak Technical Services and Viessmann’s authorized service at 444 9092. They said they would escalate the issue and keep me on the line, but after 20 minutes, I was unable to reach anyone or get a response. If a brand continues to operate this way, it is bound to lose customers. I expect my concerns to be addressed.