Nickelodeon's services are provided by:

Nickelodeon UK Limited
17 - 29 Hawley Crescent, Camden
London NW1 8TT.
Contact Nickelodeon

Nick UK's services are regulated by:

Ofcom
Riverside House
2a Southwark Bridge Rd
London SE1 9HA
contact@ofcom.org.uk

and also:

ASA
enquiries@asa.org.uk

BCAP
advice@cap.org.uk

ATVOD
atvod@atvod.co.uk