I got conned back around 2008, a lesson learned but luckily didn't cost me that much. I suspect this stuff with the claims and commission or whatever it was also applied.
At the time I was after a small run around for the missus and had decided we liked the Mitsubishi Colt, that turned out to be an ok choice as I still using it to commute to work today until it completely dies a death and it has just passed its MoT for another year. Anyway local Arnold Clarke dealership had several in and seemed reasonably priced. We went to have a look and saw one we liked.
Got to the money bit, I made it clear I could easily borrow money from my bank at say 8% APR but the guy said lets run through the figures for finance. After a bit of tapping away on the computer he announces that he can do 6% interest on HP over 5 years, naïve me thinks great better than the bank, where do I sign. Agreed to buy the car on those terms, arranged a day to collect it, returned, signed the paper work and off home with the car.
It was only later when I actually read the paperwork and realised what a flat rate of interest was. In case you don't know the 6% quoted is applied to the whole loan amount, added onto it, and then that figure is divided by however many months you agreed to pay the loan over to give your repayments. In terms of an interest rate in APR terms, where you only pay interest on whatever money is outstanding, a 6% flat rate equates to about 11% in APR. I could have got the money cheaper from the bank
Also as all the interest is added upfront there is zero incentive to pay off the loan early as it won't reduce the amount of interest you pay. Something I'd also asked the salesman about to which he replied "yeah no problem if you want to pay it off early". Thieving gits.
Anyway like I say it didn't cost me loads luckily and I learnt a lesson. No idea if I have any case to make one of these claims but I did see Martin Lewis / Money Saving Expert now has a tool to help with the process.