I reckon that I'm pretty good a googling, particularly when the thing I'm looking for (such as a BT price rise) is likley to trigger loads of posts across multiple forums and news sites.
However I can't find a single web reference which corresponds with the information in your post.
That alone would be enough to make me doubt the authenticity of the information you've been given. If you then add in BT's pledge in January that theyll not put up any of their prices until March of next year, I find myself strongly suspecting that you've been on the receiving end of some dodgy information:
https://www.moneysavingexpert.com/news/2019/01/bt-broadband-prices/