I for one am someone who tells people to steer clear of TTL at all costs, especially when you can log on the respective TOCs website and potentially save more money I.E. Unidays with LNER, the TPESTUDENT offer.
But I wouldn't say that what TTL are advertising is necessarily misleading. Below are two screenshots taken minutes ago, one from the mobile site, one from the full desktop website (albeit, on my phone):
Mobile:
Desktop:
TTL, as a premise, is quite clever as their entire business model is selling tickets, so you're greeted straight away with real-world examples of the savings you can achieve by booking in advance, put simply in percentage form.
The natural downside of a TOC's own website is that their front page will have an area to plan journeys/sell tickets, but they won't have savings at the forefront as they have a lot more to incorporate I.e. timetables/routes/policies etc.
What TTL might, to us, be a bit offhand as we all know that TTL saves you money versus buying on the day, not compared to any other website. But they don't claim to save you money compared to another website, so technically, what they're doing is above board, and their heads are above the water.
Yes they charge booking fees which is 'meh', but that's really the only downside IMO. They're not doing
much wrong IMO, and they do have an interface that works with clever marketing that also works.