What causes a Sim Lock on a mobile Mifi and refund for non delivery of services.

When to AT&T today to obtain SIM card for mobile hotspot, they activated in the store, however, it did not work. They (At&t ) staff spend about 3 hours working the issue but could not unlock the SIM Card. They connected with the Tech help desk and they could not understand the issue,. The Staff member when to the Manager and asked about a refund for the not working action and was instructed that (AT&T) does not refund perpaid activation when they cannot get it working. I am disappointed not at the staff but the Management that made no effort to discuss or explain that course of action.