Call centre terrible

I ordered a parcel online and was forced to use Dawn Wing as it was their courier of choice. When I call to find out when they will deliver the parcel as they collected the parcel from the source 2 DAYS earlier!!!, they have the worst switch board, who just transfers you the the call centre. The call centre don't answer because they are 'experiencing high call volumes'. When I do get through to a human, they ask me more questions than answer any of them. I get frustrated after holding for +10 min and tell her to transfer me to her superior. She does only for me to be put on hold for a further 10 minutes and then the call drops!!!

When I tell the switchboard to get someone to call me they don't return my call request. All I want to know is what time will the driver deliver the lasted parcel? I cannot stay in JHB CBD until 8pm for a parcel.