cellular data not working on iphone 5s

So i recently switched service plans with my service provider. But after the new SIM card was installed and set up, the cellular data did not work. The person at the store said that the phone was "too old" and will likely be this way permanently. What i mean by 'not working' is the cellular data connection shows up but it always says 'no internet' whenever i try to use the data. This also seems to have disabled the personal hotspot feature as well. My phone is an iphone 5s and it runs ios 12.5.2