Charity call centre

Heart Foundation. Used to donate to them years ago, and they now keep calling to sign you up again. Rings my mobile, I don't answer, and within 1 second they call the landline. If you say you're not free to talk they'll insist on calling you back day after day.
Very annoying.

I called back umber (07) 3606 0888 reached voice mail for a charity company but did not say the name.

i called back number (07) 3606 0888 reached voice mail for a charity company but did not say the name.

spam from some charity organisation

I called back number (07) 3606 0888 reached voice mail of a charity company but did not say the name.

It is from a charity, but they do not specify which one.
There is an option to email to them to have further calls from them ceased. Just ring that number to obtain email address.