CTA Exams

TaxBooster hasn’t been around for long, but the tutor is ex-Kaplan, so isn’t “new” so to speak.
You get what you pay for. Yes, the tutor is chaotic and is prone to rescheduling things all the time, but the courses are intended to supplement ‘real’ courses with BPP, Tolleys and Kaplan, not replace them. Anyone only doing a TaxBooster course and not a full taught course elsewhere is setting themselves up for a fail.
The cost of a TaxBooster course will get you maybe three hours with one of the higher end private tutors out there. (Private tutors are excellent, but hugely expensive - again, you get what you pay for.)
I know some people in real life who got through their resits with help from TaxBooster and swear blind by it. Others, not so successful.
Some tutors attract very Marmite-y opinions.
But I do take your point that if you’re the sort of person who likes a rigid schedule, a TaxBooster course may not be for you.

What exactly am I supposed to be advertising? All I did was point out the inaccuracies in your post...
And this is a throwaway account because I wasn't exactly being complimentary. It's well known that some people love Nit and Pards, and others cannot get on with one or both of them. They're both nice blokes, but they're acquired tastes. Deny that if you will...
I know people who have studied with Tolleys, Kaplan, BPP, TaxBooster and various private tutors, and the anecdotes vary. I don't think any of the tutors are terrible, but some of them really have distinctive personalities and teaching styles, and some people just don't click with them.
Unfortunately, none of the main three providers are willing to guarantee who is teaching a course before you sign up. I mean, you can guess at the main tutor by asking people from the last exam sitting, but you'll never be sure until the course starts. Commercially, I understand why they do that, but it's a shame for the students.
Of course, people on a GPS course have a significantly higher rate of passing the exams. Those courses are bloody expensive, so most of the people sitting them I'll wager are the ones on Big 4 contracts who are getting those courses fully funded and a shed load of study leave. So, it's not just the GPS course that makes them more likely to pass - it's all the other support that goes with it.
Unfortunately, the odds of passing CTA are higher the more money you can throw at it. I do know of a very good private tutor, but as I said, the cost of a whole TaxBooster course only equates to a couple of hours with that tutor. It's a really limited market as I don't think anyone from the main tutorial bodies is allowed to do private tuition. So, anyone offering tutor services can set their price high as there aren't many of them competing.
People in smaller firms and/or resitting and/or self-funding are more likely to try to scrimp where they can.
I think the odds of passing on a self-taught distance course are tiny, but there are options between GPS and self-taught. It's not just about extremes.
PS You say generally the main ones Kaplan, BPP and Tolleys are the best. I'm not actually sure there are any other ones offering full courses. I did look into this, and I think there was one other provider that did this in the past, but it's just been those three for ages. So they're not the main ones. They're the only ones. It's not exactly advice telling someone to pick one out of all of the available options - you haven't narrowed it down any!