Thanks! for that, I now know I may have scenarios in the future, I don't get to work on the newest models for at least 1 - 2 years (due to warranty & tlc), unless someone has a voided warranty or the vehicle has been accident damaged in some way, I can easily get access to a diagnostic machine though.
Another point is, when the reset machines are as easily available and as cheap £££££ as they are to get hold of, as they are now, then the Manufacturers do change the systems so that you have to go to them again, as I think has already been stated.