After claims that the black boxes supposed to bring down the cost of car insurancedon't work the way people would hope, the team tests them out - and Julia finds her driving skills under scrutiny like never before.Plus why some viewers feel trapped in their homes after discovering that the scheme that helped them buy their property in the first place could also make it much harder to sell.And the billing problems that have dogged drivers on Britain's busiest toll road are revealed, amid fears that the same issues will arise in parts of the country where the technology is about to be introduced.