I too have been told by a O2 UK customer services person that they do not have any O2 call centres overseas. In that case who are Pooja, Gauri, Shikha, Arbinder, Radhika, Dinesh and Rajesh? They certainly sound Indian when they have called me and have had great difficulty in nderstanding me, and visa versa.
OK, technically they may not be called Call Centres but they do sign themselves as being from O2 Cutomer Service so I think that is splitting hairs. The truth is when you contact O2 by email you get someone from India in the first instance and you only get to speak to somone from the UK after much persistance.