Why can't I use 3 network for 3G when they own O2

[Anonymous]

where I live there is no O2 3G not even edge only 2G and the O2 have no plan to do anything about it but I have found out that 3 have an amazing 3G signal round here so why can't O2 customers use 3 it's the same company ? 

[jonsie]

Yep O2-IE

[Anonymous]

Sorry yes I just saw that