DHL international bad and confusing service

There is a parcel going I think 8 times in JHB trough customs. My son in Switzerland sent us a Birthday Gift. Today finaly we got hold of DHL via phonecall: Invoice missing. Normally when you send a parcel you have to note what you are sending...Post Office or in this case DHL. This is not working between CH and SA Branches. Instead Stupid answers from JHB.