That is the "entry" level one - it is the "advanced" one that has all the bells and whistles. Costs more.
The problem that you have with adding either to your current set up is that it is possible that you don't have the loom connectors for W-Bus operation so you would have to rework the loom or buy a new one - all the later ones should have it though, I think that it was just a few that had the old ST loom instead of the new one. They are certainly present if you specify the Multicontrol instead of the rheostat. Look for a small connector like in the pic with a red. brown and yellow set of wires, it should be labelled Thermocall/Telestart/Diagnosis.
This is a Telestart that I have just rewired a ST loom for to show connectors ( different colours as 12v operation not W-Bus here), it is the same for a Thermocall.
To install - plug it in, tuck wires/hardware away.
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