I called back number (07) 3569 8288 reached voice mail for a charity company but did not say the name

Charity voicemail

I am getting calls every evening from either mobile or landline. This was the latest. They hang up if I answer or go to VM but don't leave a message if I don't answer. Originally I bought something from the Leprosy Mission and every since have been harrassed by them and other so-called charities!