iPad mini retina LTE. sim not hot-swappable afterall

I purchased the t-mobile iPad mini retina LTE today, lured by the 200 free MB for life offer only to be disappointed in the uneven t-mobile LTE service. I had 10 mbps down at school, 24 mbps down at home, but it reverted to 4G at my brothers house whom lives only 4 streets away from me! The speed at my brothers house was a paltry 1.9 mbps. I will admit that the 24 mbps was amazing but I could probably live with 10, what i can't live with is the inconsistency of the service.

I went down to my local Verizon store and the attendant took my device and attempted to setup Verizon service to no avail. He entered the ipad data (i assume the imei and other info on the 'about' section) into his system but told me that it didn't recognize the ipad. He claimed it was locked to t-mobile. He had taken out the t-mobile micro sim by that time.

I was under the impression that all new iPads were the same sku. any insight would be appreciated.