Telling mobile are useless

Sonafternusing a contract phone for 18 months. I get a SMS saying Sim swap in progress. Now the phone doesn't work. My ex partner blocks a phone he gave to me? Really. Do I sue him or telling for loss of earnings? Went to a telling store today. They can't help me. 🤣🤣🤣 How many cell phone ******* go to the supplier?