Thank you all for the thread, it helped me solve my problem. We had the same on our bank statement, and it transpires that it was due an over the limit letter from TESCOs credit card, and unfortunately used the number provided rather than going direct to TESCO, and the number was... you guessed it, the collection company. So fortunately we hadn't been conned for £1k which we thought we had, but am a little unhappy we made the mistake of using the number on the letter, because numerous banks will not touch people who have CCS RB collection on their statements.