Never-ending Toyota Problems

I am a 2022 Model 1.5 Dream package Toyota Corolla user. Two and a half months ago, I took my vehicle to the Toyota Authorized Service ALJ Automotive in Çekmeköy to have its 30 thousand maintenance done and to show the fault I noticed on the temperature gauge. My vehicle's maintenance was done for 8,900 ₺ and the fault was detected. It was stated that the vehicle's thermostat was open and therefore the temperature gauge dropped, and it was said that the thermostat needed to be replaced. We requested the thermostat to be replaced. It was said that an order would be placed and the replacement would be made, and that the vehicle would need to remain in the service during this process. They called 1 day later and said that the thermostat part would come from abroad, that the replacement would be done as soon as possible and the vehicle would be delivered. About 40 days later, they said that the thermostat was changed and we received the vehicle. However, the vehicle had the same fault again 1 day later. We took it back to Toyota ALJ Automotive in Çekmeköy, they said that there was air in the engine and that this had been fixed. However, the same fault recurred a few hours after we received the vehicle. We took it back and many excuses were made. The problem could not be solved. Finally, 40 days ago, I took the vehicle back to the same service, this time they said that a part called the bypass valve was broken. They said that this part also needed to be changed. We dropped the vehicle off again, and they said that this part would also come from abroad. It has been 40 days and we are still waiting for the part. We have been waiting for the vehicle's fault to be fixed for a total of 80 days. Since it is a vehicle with a warranty, they are implementing a policy of stalling and harassment. Toyota and the service have inadequate customer relations. I have not been able to use the vehicle for 80 days. We call Toyota, they direct us to the service; we ask the service, they blame Toyota. They do not even know when the part will arrive.