If you want whataboutery then:
what about telling us when this person left and how broadly their usage differed from yours and your wife's?
what about all the tariffs with no exit fees which mean you could switch back to a standard tariff at no cost?
what about how easy it is to test sensitivity to differences in expected consumption (say + or - 50%) very easily with a spreadsheet of your own or by sticking different figures into a comparison site?
and indeed what about explaining why you thought you had irregular readings that didn't give you a baseline for comparisons?
It seems to me nothing at all like that because you start with the millions of people with empirical evidence that switching is easy and saves money. (And also because I'd have thought the starting point for weight saving would have been the driver/rider. Cf coxes in eights before the days of minimum weights.)