Hi Karla,
First things first a very warm welcome to the eForum Family, I only wish it was under a happier cloud
It sounds to me like it may be a firewall or process that is blocking your connection to the internet. Have you had a chance to test the modem in another PC or laptop to see if the original connects ok then? Have you had any service updates or security software installed since the modem was last used? As it sounds like the technical team went through the usual SIM update details to get the network to recognise the card, it would seem like a hardware fault.
I can understand if you didn't have time in this case to let the store look at the original one for you but the
Repair Process if it is the modem is always the best route to go; that way they can tell you if there is an issue with the card by trying it in store on devices too.
Cheers, Ben
eForum Team