This number calls me, and never leaves a message. Who are they and what do they want?

Caller: Drive Yello

This is Drive Yello, part of the delivery app Yello

I called back number (02) 8417 3050 rang once then goes to busy otne.

I was self-isolating on the health advice of doctors on the afternoon between August 12th and August 14th. I received a call from this number during this period. The legal requirement is to self-isolate until test results arrive from the laboratory. I called back this number, which directed me to an automated telephone message belonging to DriveYello.

I called back number (02) 8417 3050 rang once then goes to busy tone.