I've faced an issue yesterday. I bought a 7-day hotspot ticket on the 22nd of August, which is basically the day before yesterday. After a couple of hours I decided to redeem it, and everything was fine for a several hours, until I disconnected myself. Afterwards I wasn't able to reconnect, due to the fact, that I must log-in, or buy a new ticket. It just no longer recognizes my mobile phone.
I bought and redeemed the code from the same device. Despite what I do, I just can't connect.