Sorry to hear that you're having trouble with your free trial subscription.
Please keep in mind, Pandora accounts follow the email address, not the device or phone number. You can sign into the same Pandora account on any computer or supported device, as long as you use the same email address and Pandora password. This applies to both free and paid Pandora accounts.
I've escalated your case to our User Support team. Someone will be contacting you via email shortly. If you don't see the message soon, please check your spam / junk folder to make sure it didn't end up there.