My birthday present doesn't work

My birthday is approaching and I had originally requested a photo printer from my husband but changed my mind and asked for an air card of my very own so I can get on the Internet, too. When we decided on the T-mobile service last year they had the lowest monthly rate and promised coverage along the major freeways. We’ve had problems the past couple of months and Verizon has much better national coverage. They have a card that is only $50 so we stopped by with my computer, made the purchase and installed the software while we were standing at their counter. Then my computer wouldn’t reboot and we were stuck. They can’t touch my computer so I asked for a repair service recommendation. They sent me down the street and the tech sympathized and said for $25 he would diagnose the problem. Hope it’s a simple fix. At least get to a point that I can uninstall the software and return it for a refund.