My phone keeps calling my sister

Hey for the last month my phone keeps calling my sister, it can happen even when my phone is on charge and I haven’t said anything, or if I’m watching Netflix it pops up calling her, I’ve deleted her number, blocked her and she’s even blocked me but when my phone calls it still shows that I’m calling her rather then sending it to voicemail, I don’t have my phone set up to voice call her or for speed dial, it’s come to a point where I’ve now had to set it to airplane mode at night as it was sometimes calling her while I was asleep at 2-3am, I even tried resetting my phone.