15GB/mo mobile hotspot @ $10/mo with 2 yr commitment??

Hi All, 

The end of last month (May) I found this T-Mobile promo for a LINKPORT IK511 cell modem and a 15GB/mo plan which for a 2 year commitment boiled down to a $10 per month bill.  That's what the sales guy stressed and to not worry about what the bill stated, it was $10/mo.  (I no longer see the promo on T-Mobile's website for current nor past promos which can only complicate the matter.)  Ok, a few weeks later I'm seeing a $15 bill.  Don't know why as he ran a credit check as part of the approval process and I provided a credit card to be billed for the $10 monthly charge.   So one disconnect on the monthly cost and another on why I'm seeing an outstanding bill when the credit card should have been charged.  Then today I get a letter from "T-MOBILE FINANCIAL" stating they need additional identify verification to complete my application?  What application??  I did the credit check with the sales guy and thought that was the end of it.  Any idea what is going on here?  This is my first dealing with T-Mobile and not at all getting a warm and fuzzy new customer feeling in all of this.  Am I just overlooking some well known quirk in the process or do I have a mess to sort out as it otherwise seems?  I haven't contacted T-Mobile customer service thus far given the late hour and preference to get a domestic agent during normal business hours.  Also I figured the collective customer brain trust would be able to provide guidance for this issue which may not be forthcoming from T-Mobile.  Thank you.