Process of NGOs to ask donation is messed up, what's better approach?

Just realised the way many NGOs are working are messed up.

I got a call for help, they shared some documents of kid who needs help,I verified and donated some amount with in my budget.

After few days, I got another call, I verified the details and donated.

Now am getting 10-20 calls daily. I asked them,how they are getting the number.

Someone is taking care of the making list of possible donors, who already donated or possible to donate - after little push. The NGO worker or person working on contract have become expert on manipulating emotionally. I get it, they really need money for patient. But is it the correct way to bombard someone 100s of calls daily ?

Am tired of putting them on blocked of true caller. Now I just don't pick.

I was happy once to help,now I regret.

I wonder what's a better approach for NGOs to get donors ,without irritating 1000s of people by calling them.