This is why I stopped buying in the store and started buying online. In the store, they are NOT happy with people like Droid800 and I who pay full retail price. Which is fine, because I realize they are commission based, but it always seems to really show in their faces and attitudes.
As far as the whole activation piece, remember you are not activating a phone you are activating a SIM card on your account. The two are completely separated from each other. Once that SIM card is activated you can stick it in any 4G phone and it will work. That is why there is no *228 OTA programming with 4G phones. So you have 2 options:
1) Have them activate the SIM on your account in the store. You will notice the SIM card is pulled from a cabinet not from the phone box. If you want to verify they did the activation correctly they can put it any 4G phone (e.g., demo unit) and test before you leave. There should be no arguing about this. If they do, it's likely the rep just isn't fully trained yet which is not their fault.
2) Buy the phone, have them hand over the SIM card and activate the SIM using the 888 number.
If you're concerned it won't work, have them plug it into a demo phone and make a call with it before you leave. If it doesn't work, that means they set your account up improperly.