My family is calling my home constantly? - 2

They're envious people and call us many times a day just to annoy and take our peace away. I'm thinking of buying something to proof their constant calling and what's said on the callings.

Thing is my cellphone doesn't register many received/missed calls (just 5 or 6) so I'd like to know if there's a cellphone out there that does so, so that I can buy it. Iphone, maybe?

Another thing is, if I buy a voice recorder, will it record just the voice? What would I do about the hour of the calling? Can a voice recorder inform the hour as well?
Will a judge accept the hour I've set in my recorder/cellphone? Or will it just accept an official hour? If only official, how can I find an official thing to inform the hour of the calling?

Would a micro-camera be any good? Should I install cameras at my home so that I can record when they come to ''visit'' us?

Sorry, I'm just 22y.o. And I've been facing them over the last 5 years, since I lost my dad. Things got worse lately. Even my mum got ill. I must do something. Thanks in advance for any tip.

Added (1). I asked this very same question last week and was advised to change our number. Well, we changed our house phone number and let just 1 cellphone number for them to call. They keep calling us in the cellphone every day. They tell minor excuses as reasons to call, such as ''I'm calling just to know if you're well''. I feel monitored. Please, help?

Added (2). We haven't got rid of them yet 'cause they're the only family we have. Don't know what to do.

There's no law, anywhere, against hanging up the phone. Try it. You won't be arrested.