I suspect that all the broadband supply companies, are continually changing prices.
Yes of course. The price goes up, and then the price drops so they can advertise this as a "discount". You can expect prices to go up for a month or two before November, so that people think they're getting a good Black Friday deal.
Not all broadband suppliers play this game. I'm with Aquiss which has level pricing in and out of contract, and between new and existing customers. The only thing which varies is their introductory discount, which moves between 3 months and 6 months at half price (currently 6 months).
But if you've re-signed with VM (or are resigned to VM) then this isn't of interest to you any more. With VM you have to play the end-of-contract game every couple of years - threaten to leave until they give you a reasonable price. Sometimes they will, sometimes they won't. It's an anti-loyalty scheme.