Disrespectful collector national debt connection

National debt collection I been receiving harassing calls sms and what's app messages from this company first with no verification of account secondly no introduction and lastly they have not followed the popia act rules and regulations a consultant has been what's app me from 0791994637 did not introduce them selves I tried making arrangements due to my financial situation they have no listened to me and respected me refuses to listen to and to be symptoic towards me showed no remorse but only threaten me I have the shot of conversation they have contact my work place with the popia act I give no content the utter rudeness threats on what's app I know my rights please assist me