Every institute that promises a band is promising something it does not control, and the promise is always made before the fee is paid.
The most common question at the interview is what score this course will get somebody, and the honest answer costs us enrolments. We give it anyway, so here it is written down.
We do not know. Nobody does. The test is sat on a day we are not there, marked by people we do not employ, against criteria applied by human beings, on tasks nobody has seen in advance. Between the interview and that morning sits ten weeks of what a student does between sessions, which is the largest single factor in the outcome and the one entirely outside our hands.
What we can see is the marked work. Two written pieces a week, marked against the criteria the test actually uses, and a recorded speaking task every week. After six or seven weeks of that, a teacher has a fairly clear picture of where somebody is and how fast they are moving, and that picture is the basis of the one prediction we do make: sit the test on your booked date, or move it.
That conversation happens in week seven and it is the most useful thing in the course. It is also the moment where an institute's incentives and a student's diverge, because the comfortable thing to say is always yes, sit it, you will be fine. A student who sits too early pays the test fee twice, loses six weeks and sometimes loses a place. A student told to wait is annoyed with us for a fortnight.
So the rule here is that the week seven judgement comes out of the marked folder and nothing else. Not how much of the fee has been paid, not how close the departure date is, not how much the student wants to hear yes.
One more thing about promised scores. When you see a guarantee, read what it actually guarantees. It is nearly always a free repeat of the course rather than the score, which means the institute keeps the fee and you lose the ten weeks, which were the thing you could not get back.