Call centre that keeps calling with slightly different numbers after I block them

Caller: Scsmmer

Just ask them to hold and you'll be just 10 seconds, put the phone down and let them waste their time until they lose their mind.

Called a number of times with slightly varying numbers like 0485 993 861 and 0485 994 335, kept saying hello on the other end without asking to speak to a specific person. Very suspicious.

Called with slightly varying numbers, like 0485 993 861 and 0485 994 335