Just had a call from my 80 year old mum really upset keep ringing and are very aggressive

Only 3 calls today told them many times I'm not interested what they have to say but still keep ringing. I just don't answer anymore.

01613028213 when answered gave out recorded message saying ring back 01618148662!

Trying to sell funeral cover. Won't take no for an answer and keep calling back.

How do i block this number get loads of calls from them and ive asked them to stop calling me they dont listen im 68 years old i dont want to talk to them