Question for CTVTF340 (Added 20/10/14 )

Is the high temperature cut-out available as a separate part?
Have reset it ok – it def has not seen overtemperature, is installed horizontalIy and head is not lagged.Is about 2 years old, in a new-build house.
Looks like the device screws in the flange, but I may be wrong? (I am familiar with the the other sort which are integral with the removable control stat).
Ref number is – Thermtec CTVTF – 340. Which you show as superseded.
Thanks for yr advice