I recently purchased a 6620L Jetpack device on the newly update $70 per month unlimited plan. Unfortunately the performance has been awful, with speeds consistently around 200-500 kbps. I asked the store about a return, but was told that this is not possible, even in the 14 day initial window - are they correct in stating this? Is there any recourse, or am I stuck with a $150 device that is barely usable?