Iphone from Ebay, Need Warranty Exchange , Activation - COMPLEX SITUATION !

[badphone]

OK, here is my situation. Right now very complex but may be there is an easy way out.

Im a T-mobile customer, bought an Iphone 3G on ebay. The seller said, its brand new but apparently it's used but pretty good condition. The issue is, it has a small crack around the headphone jack. I didn't wanted to deal with return/refund as it was a good deal even though misinterpreted..

Checked the Serial# and it's in warranty for another 8 months. Did some research and apparently it's an issue with some 3G phones and I took an appointment with apple store and asked for replacement.

They nice lady looked at it and had no questions and said she is aware of this problem will give me an exchange. She checked serial and pulled a refurbished iphone and almost done trying to complete the exchange.

Then she realized that there was no SIM in the old phone to activate the new iphone !!. I was like " I didn't bring my SIM'.
So , basically I came back stating that I will return with the SIM. She wouldn't give me without activating. I was kinda embarrassed but thats what ATT-Apple is doing for non-ATT folks who want to use iphone.

So, What are my options here guys. Help me.

1) Do I need to take ATT customer and use her/his SIM to get the exchange and activate
2) Will it cause any issue to their account ( Extend contacts, their iphone gets locked or something like that)
3)I have ATT SIM from work ( Just data, no voice service). Can apple store use that SIM to activate ?
4) I got tired and jail broke/unlocked it now and started using on t-mobile . What steps I need to do before I go again.
5) When I jailbroke, I installed cydia and Icy which should not be done. ( only one should be installed) So I did a factory reset to re-jailbreak and the damn phone got unactivated. Somehow I was able to activate it by using a backup that I took before I started jailbreak. Will factory restore put the phone in unactivated mode ??

Please answer as much as possible. I cant believe Im going through this , just to use a phone on t-mobile paying $400.

[cpjr]

Yeah they are full of crap.

Per Apple's own warranty agreement "Warranty is NOT dependent on activation".

So you dont need a simcard for an exchange, I've swapped many without one.

[angiepangie]

You don't need the sim/have to have it activated to get it swapped.
Some 'geniuses' are just... well you know

You can try borrowing a friend's sim or buying one of those $10 pre-paid phones...

[ruslan120]

Will Apple service a 4S I bought off eBay that was on Sprint but now is not on-contract? That I can claim "has been used as an iPod?"