I also received something similar from LCS demanding I owe £4600+ in interest and charges for a closed ADCB account. When i asked them for a statement to show how they came up for that figure ADCB did send it via LCS, but my debt was then drastically reduced from £4600 to a mere £60. I did have a ADCB account in 2009 and they wrote to me 10 years later saying it wasnt closed and fees were due etc.. Long story short, after many email back and forth, and the fact they couldnt access any further account details as they had been archived all the interest charges were written off except for a 300 AED cheque return fee. I decided to pay this in return for a Clearance Letter, which is vital as it means ADCB could not chase me for any further amounts in the future in relation to the closed account. Usually DCA's are crooks who cant provide any details and just want to harass you but I found LCS to be quite good in the sense they responded to all my emails and did actually liaise with ADCB on my behalf and provide everything I asked which was available to them. It's totally your choice what to do but if you know you had an account with ADCB in the past and know you might owe something ask for a account statement and see what it shows.