That’s interesting, same deal I got for my son but in Durham it says £29 a month!
Weirdly I’m sure when I chose it on Broadband Genie it said £26 with a £60 voucher, now says £28 with a £50 voucher!
Unfortunately I haven’t had anything from them about it at all, only from Vodafone which says it’s £29 (plus a £3 rise each April) 🙁
Please excuse spelling/typos. Apart from being a clot it turns out I had one on my cerebellum that's now causing various problems!