O2 customers will have to get themselves to an O2 store if they want to have any chance to get their hands on an iPhone 4S on launch day.

On its official Twitter feed, O2 revealed that it would not be taking pre-orders and customers would have to go to one of the company's stores to get an iPhone 4S on 14 October.

"On launch day, you will not be able to upgrade online. You will have to get along to your local O2 store on the 14th October," the company said.

"Only existing O2 customers will have the ability to upgrade in store, on a first come, first served basis," it added.

Details of tariffs haven't yet been revealed, despite the fact that rival operators Three, Orange, T-Mobile and Vodafone have all released theirs and are all taking pre-orders as well.

Predictably, many O2 customers are unhappy and have expressed their discontent on Twitter.

"I am an existing customer, that doesnt help the fact I have a job to be at on Friday, tarrifs better be good to make this mess justified," one wrote.

"Sorry, but that's a real kick in the teeth to those of us who have been loyal customers for years," wrote another.

O2's press office hasn't responded to Macworld's questions on the matter, but the company will have an online stock checker that'll be live from 14 October so you can see if it is worthwhile making your way to your nearest O2 store.

UPDATE 1815BST: O2 has confirmed to Macworld that the iPhone 4S will only be available in store to existing customers on 14 October and said that it would be releasing pricing details "well in advance of the iPhone 4S going on sale".

UPDATE 8/10/2011 0830BST: O2 released its tariff plans late last night. More information can be found on O2's website.