Parcel at JHB International

Hi there

My parcel has been at JHB International mail since august. We paid for the express parcel but unfortunate the company that send the parcel put the wrong label on and now my parcel is stuck at JHB International mail. I have been trying to phone the number ********** and there has been no answer or you hear how the person puts the phone down in your ear. I have send mails and all response i get is that they do not have the parcel and that they have a backlog. This parcel is of utmost importance and need this before the end of the month. How do i follow up if nobody answers the phone. There is no manger in charge and nobody that can assist? How is this possible