Q: Cellurar Data - Mapping services

Hey there GiorgosAU,

It sounds like you notice that a service is using your 3G connection when you enable cellular data. If you are referring to the Maps app using your data, you can disable Maps in the Cellular settings on your phone:

Choose Settings > Cellular to view the cellular data usage for each app. Tap to turn off cellular data for an app. Contact your carrier if you have questions about your cellular data usage.

iPhone and iPad (Cellular Models): Understanding cellular data settings and usage

http://support.apple.com/kb/HT4146

If you are referring to Location Services, you an also disable that in your Settings here:

Settings > Privacy > Location Services

iOS 7: Understanding Location Services

http://support.apple.com/kb/HT5594

Thank you for using Apple Support Communities.

Cheers,

Sterling