I understand you being frustrated.
Lets try this a different way.
Velleman’s Part number is NTCMJB2/SP.
Just looking at the part number tells me it’s a NTC Part Number.
the /SP I think stand for Spare Part.
Searching for just NTCMJB2 bring you back to Velleman.
How ever I did a search looking for NTC MJB2.
I first list gave me the specs and what the numbers were all about (info below)
The next few listings were pages on Ebay.
MJB2 series NTC thermistor is one where the thermistor chip is welded with leads by alloy soldering process, then partially treated by glass sealing. The element has a bead form with good stability, small size and rapid response.
The suffix number of MJB (0, 1, 2, 3,…) represents the dimension of glass head. The characteristics for a series of products with different suffix are expressed same. So, no difference is made in the introduction to this type.
Like I said I have no idea of where you are but maybe you can find on in your area.