I'm being threatened over the phone on a private no!!

I know this shouldn't be here but I don't know what to do, since yesterday at 6pm a guy called telling me he's from LLS (which i have heard from some friends after telling them that it is a gang, I'm not involved in this stuff if this is the case) 3 times threatening me that he's going to throw acid in my face and I could hear other guys laughing in the background. I put my uncle on but he kept calling back I told him not to call me again, and at 5am he was calling me all over again!!

I'm very private with my number and have only around 20 contacts who I have willingly gave it too....I'm not sure if a friend has given it out but he keeps calling me and threatening me.😶 what do I do its a private no is there any way to find the caller behind it! And what would you do!!!

(I'm from england)