You should have given more information than just the number. The instructions before posting are here:
http://www.saynoto0870.com/cgi-bin/forum/YaBB.cgi?num=1107463510

However, the company behind the 0845 845 4567 number is DNA Forensic Nursing in Leicester. On their website they don't divulge their address but it is possible to find it. They have 3 addresses but I am not sure if all of them are current.

DNA FORENSIC NURSING

Unit 9, Wetsleigh Business Park, Winchester Avenue, Leicester LE8 4EZ
phone 0116 229 3115 or 0116 278 8387, fax 0116 229 3015


504 Aylestone Rd, Leicester LE2 8JB
phone 0116 283 9699

Boston Rd, Leicester LE4 1HB
phone 0116 229 3115 (same as the Winchester Ave number)

Try the geographic numbers given and please let us know how you got on.

Could you let us know which of the numbers worked so we can put them in the database?