Many Zimbabweans have their passports about to expire in the next two months, with no facility for renewal before the expiry date. I suspect the Zimbabwean consulate cannot accommodate the workload. The consulate requires an appointment to be made to renew a passport, but it has no appointments left.
After 10 days of unsuccessfully trying to make an appointment online (the only method available), the consulate has now implemented a new strategy of only being able to make bookings online between midnight and 4am. Sadly, one cannot actually make an appointment then either. At no time from the first second after midnight onwards does the portal give access to any appointment options.
Trying to telephone the consulate office directly is equally futile, as I have personally experienced over the past 10 days.