"I went on line on another site to check the t & C".
Well there's your problem then. It's not Tesco you should be moaning about but 'the other site'.
You should always check information with 'a primary source' (i.e, in this case, Tesco's own website):
"Excludes Wine Route, boxed/fortified wine, bottles under £5 in Eng and NI or £7 in Wales & bottles under 200ml. Minimum unit pricing applies in Wales Max. 36 bottles, while stocks last. Excludes Express & Scotland. Ends 01/12"
https://www.tesco.com/groceries/en-GB/promotions/A32911398