I have Spotify PREMIUM through my phone contract. It stopped working suddenly last week. I contacted my phone provider, and they confirmed I have Spotify Premium until October 2017, but I only have access to the free version. It had apparently been cancelled from my end, but I have never logged out or cancelled my subscription. I've tried logging out and back in and having the same problem.
Welcome in the Spotify community! First you should check your subscription status here. Is it premium or free? In general if you have a problem with premium which you got through a 3rd party (here your phone provider), you have to contact the support of your phone provider. Spotify unfortunately can't help you to fix premium problems of 3rd parties.