The box needs to be professionally fitted, otherwise any information it transmits may not be reliable, credible information. It's very easy for a black box to loose a signal (they work on 3G phone data). If it loses signal, it then looks like you've teleported through time and space (often registered ridiculous speeds). There have been multiple cases like this reported to Watchdog and we wrote about on reported to us here: www.honestjohn.co.uk/news/miscellaneous/2017-09/dr.../

Raise a complaint and ask for them to provide all the data from the box. It is their responsibility to ensure it is fitted correctly, not yours. I cannot see how it can work if it was wrapped in a tea towel and placed in your glovebox. Also take the claim to the Financial Ombudsman.