Almost half a million people file complaint after Martin Lewis warning for car buyers before 2021

It's only been a few days since Martin Lewis launched his free tool to help car buyers who got a vehicle between 2007 and 2021 see if they're entitled to some money back - and thousands now look to be in line for compensation.

Last month, the Money Saving Expert revealed that 'billions' could be owed following allegation of some unsavoury business practices.

In fact, analysts at Jefferies calculated around £13 billion might have to be paid out by the industry, according to the Financial Times.

We'll let the finance guru explain it himself in the video below:

Speaking to the BBC, Martin Lewis explained what had happened to potentially leave customers out of pocket: "​​What was happening at that point is the lenders who organised the finance were saying to the car dealers 'the commission is discretionary'.

"In other words, if you want more commission on these finance products - which is why they were being more heavily sold - you can simply increase the cost of the finance and you will get more commission.

"Many of them did so and it wasn't declared, so the consumer was not aware quite what enormous sums were being paid in commission to car dealers for this type of finance."

So, if you bought your vehicle with a Personal Contract Purchase (PCP) or finance agreement then you could have been charged more than you ought to have been.

The Financial Conduct Authority (FCA) has launched an investigation into claims that car dealers were told by lenders that they could get more commission money by increasing the cost of finance.

If that turns out to have been the case then you might have spent more than you had to on buying a car so the dealer could get more in commission.

Lewis has said he doesn't think the FCA would have investigated unless they were confident of finding wrongdoing.

To help car buyers potentially get some money back Lewis and his team at Money Saving Expert created a tool which will create you a complaint letter if you put in your details.

The day after he launched it (7 February) over 130,000 drivers had used it to create a letter of complaint, a day later (8 February) and that figure had pretty much doubled.

Last night (9 February), Lewis tweeted that almost half a million people had used the tool in the first three days, which means the payout pile could be pretty darn substantial.

According to the expert's estimations, around 40 percent of people complaining were charged more than they should have been and will be eligible for some money back.

He also said that the average payout in these cases would be expected to be around £1,100.

It's not an insubstantial sum, so you best hop onto Lewis' tool here if you think you're due a payout.