Help, my ex keeps getting my new phone number

I've changed my number 3 times and he somehow kept being able to call me, I had an Android Motorola so I just changed it, then I had a ZTE (figured since the brand was so different he wouldn't be able to get it) AGAIN he got the new number, changed it one more time and he got it again. Now I got a Samsung Galaxy, new number, I've had the phone less than a month, my mom passed away AND HE CALLED ME THE DAY OF HER FUNERAL AND TWO DAYS AFTER FROM A DIFFERENT NUMBER.

I'm getting scared and angry, this person was physically and mentally violent. He's controlling, a liar a psychopath and just incredibly manipulative. I considered a close friend maybe sharing it with him but that's just not possible, I have given my new number to maybe 10 people and 3 of them are friends that know in detail the damage and abuse he did and ABSOLUTELY HATE HIM. So no I don't think it was any of them, my family either cuz they despise him, and I may ask my friends but again, I just find it unlikely since they literally begged me for his address cuz they wanted to get more people and go all together to beat his ass. I'm not immature and I don't believe in violence so no, I didn't give anyone his information, but I told his parents the second time and they legit took one of his phones and broke one of his chips too so that he wouldn't be able to contact me (which worked for about 4 months). I'm not afraid of him doing anything to me, he doesn't know where I live and I've not ran into him but once in the year we've been broken up, so I'm not sure if getting a restraining order is an extreme measure or if it would even go through. Is there any way he could be getting my number? Should I contact his parents again or just get a restraining order? (His parents legit told me to dump him, that he was an idiot and that I was way too good for him, they also helped me a lot even after the break up) I'm just running out of ideas and can't afford to get YET ANOTHER PHONE TuT

Edit: I had so many grammar errors, I'm just so anxious and overall stressed, sorry. If something doesn't make sense please let me know so I can clarify