Radiator is not reacting to reduce temperature

Hi all,

I have 4 tado radiators which I bought 2 years ago. This happened with 2 of them with 1 week distance. Both have new batteries and were working properly so far.

While the temperature I had set in the all was 18 degrees, the real temperature was 30 and the radiator was not reacting to reduce it.

Could someone help?

Thanks?
Dimitris