Neither of the things you mentioned were happening on my car, it wasn't driven like a fanny and the settings weren't even moved from your stock settings! It also wasn't driven at 30mph in 6th either. It's a generic box that doesn't always suit every car but blaming customers is a cracking level of customer support so well done.
To be honest customers can be/ and are to blame for a lot of issues, as some simply don't listen to our advice and then end up slagging us off online, but there again we do live in the age of the "keyboard warrior"
18 months ago we started adding stickers on the front of a module and a warning on the front of the instructions asking customers to contact us before they start and play with the settings, id say at least 70% of customers actually do email us and its saved a lot of issues. But the 30% seam to miss both of these things and then wonder why they're having problems.
5 years on from the 2.0 GTD 184PS being launched and were still tuning as many as we were back in 2013, so we must be doing something right