Caller: Clever contacts

Constantly ringing me, even though I'm on the "do not call register". I block their number and they ring from a different one. They just don't stop.

Continuously calling day after day. haven’t answered any of their calls

8 calls from this number at various times of day over last 10 days. Do not recognise number so don't answer. Caller does not leave a voice message.

Has been calling almost daily for several weeks. Never leaves a message. Extremely annoying.