You need to check your paperwork, and speak to your bank.
Back in 2008, one of the ways I sought to finance my PhD was by taking out a career development loan. It was probably not a good decision - I had no face to face advice, and reliant only on what I could find online rather rushed the application. I applied for too small a sum, and did not really take in the fact you had to pay it back after three years - regardless of whether you were still studying or not.
Paying it off was grim - I spent most weekends and all summer in 2011 and 2012 doing security work at various sites across London and the south east. Studying had to wait. In a lot of ways though, I learned as much from that as I did from my own research - about how people act in crowds and groups, when violence starts, how big corporations work and do not work, and the impact of globalisation.
At times it was hard not to laugh out loud - working with a group of Pakistani 'students' from a G4S subcontractor, I casually mentioned that I was not only a mature student but worked at university. Near panic broke out in the ranks as their unofficial foreman began shouting to the others in Urdu - no doubt warning that their cover stories could fall apart if anyone spoke too much to me! Later I received the regular email from Sir Edward Acton, Vice Chancellor of the University of East Anglia, where he kept staff informed of his determined lobbying against the Home Secretary's restrictions on student visas. Sir Edward would never see the world that I had, and could not grasp the main reason such employees are low paid is the bottomless pool of workers (some pretending to be students, especially at language schools) entering the country daily. For them, the minimum wage is a fortune.
On Saturday morning I went downstairs to find a letter from my former bank, declaring they had wrongly charged interest on my career development loan, and incorrectly charged me on the occasions I failed to meet monthly payments. A cheque for a four figure sum was enclosed. In some ways I am very lucky - had the bank sent it to my old address, I would never have received it. In others I reflect on how much easier life would have been without the ball and chain of interest charges. I would certainly have finished my PhD sooner, and would be further down the career path I want to get too.
If you used a career development loan to help finance your PhD, do speak to your bank about the interest payments and any charges. You may be due a significant refund.