Questions of Cash: My son couldn't drive the hire car he had paid for

Q. My son booked a Budget hire car via ebookers.com to pick up a car at Dublin Airport. He completed an online form confirming that his age was between 21 and 24. At Dublin he was told by Budget they could not let him have the car as had not been driving for eight years, yet he had paid extra because he is under 25.

When he got in touch with ebookers, it said: "This booking was made by our website and therefore you were acting as your own agent", and added that the ebookers' terms and conditions state that you cannot hire a car in Dublin if you are under 25. We checked and found this, in very small print. Our son should not have been able to make the booking and once he gave his age the website should have prevented him going further. My son was promised a refund of the car hire charge – though not the additional costs incurred – but this has not happened. JK, Leicester.

A. Your son initially logged on to TravelSupermarket, from where his enquiry was redirected to ebookers. This seems to have caused difficulties for the online booking system. A spokeswoman for ebookers explains: "On this occasion the booking originated through TravelSupermarket where the search box for car hire has a default age option of 25-70.

When coming through a comparison site and the prerequisite is already selected, the customer would land on the ebookers page where the supplier – Budget – and location are already confirmed. When booking directly through the ebookers site, customers are asked to provide their age first before booking options are shown ... We understand this was an unfortunate circumstance for the customer and have provided a full refund on his booking."

Why is HMRC sending debt collectors?

Q. HMRC claims that my wife and I owe them £407.43 for overpaid tax credits. I have repeatedly and unsuccessfully asked for the calculations. My wife no longer has bank statements for 2006/7, the period concerned. HMRC seems to be confused as initially, in 2012, they suggested the overpayments related to the 2003/4 and 2004/5 years, but now they are referring to 2006/7. The debt is to be collected by a private debt collecting agency, so our credit rating will be affected. AN, Newcastle.

A. A spokeswoman for HMRC explains: "The overpayment occurred from the 2006/7 tax year. We paid [the reader and his wife] £3,488.53 and they were only entitled to £2,274.71. This was due to their actual income being higher than the estimated income figure they provided to us. Some of this overpayment – £401.50 – was remitted due to official error, but the outstanding balance of £812.32, which is not official error, was due for recovery.

We recovered £404.89 through cross-award recovery [a deduction from other payments], leaving an outstanding overpayment of £407.43. We wrote to [the reader and his wife] on 11 March 2009 ... The award notices sent to the couple, dated 19 June 2006 and 5 July 2007, would have clearly shown the overpayments for the relevant years, and broken down the amounts involved. [The reader's and his wife's] claim ended on 31 August 2007, and we asked them to pay the outstanding overpayment on 27 June 2008.

They questioned the overpayment and we wrote to them in June 2012, [and in] January and May 2014, asking for evidence to support their dispute. They have not provided us with any evidence. As there is a time limit on disputed overpayments, [the reader and his wife] are now unfortunately out of time to formerly dispute this overpayment. If a claimant reports a change of circumstances which means they have received more money than they were entitled to, they must pay it back.

Questions of Cash cannot give individual advice. But we'll do our best to help if you have a financial dilemma. Email us at: questionsofcash@independent.co.uk