Possible Hack!

My phone (Iphone 12Max Pro) having worked perfectly for several days since I switched to Smarty I am currently unable to receive or send voice calls or SMS messages.This reminds me of my previous provider, who allowed a hacker to add an Esim to my phone, thus disabling the physical Sim card, Without access to SMS texts, I am unable to provide two-step verification for internet banking or on-line shopping.I looked at Settings on the Iphone, but nothing looked wrong. Any ideas what the problem might be, or how to resolve it?