Customs is coming under pressure from the steady loss of staff who have opted for state severance packages.
Most of the officials who are taking advantage of government's generous early retirement scheme are said to be senior to middle-management level staff. Recently commissioner Daan Colesky handed in his resignation.
Durban acting customs controller Joe Britz has said that while junior levels were filling up, senior staff were steadily leaving the service with no signs of replacements.
The resignations come at a time when customs is filling vacancies at border posts around the country. More than 350 customs officials have been hired over the past year.
The appointments were intended to fill vacancies that had built up over the past few years and resulted in understaffed border posts losing control over smuggling and customs duty evasion.
However, government's drive to reduce the civil service through voluntary retirement and by limiting the number of replacements has cut into senior management. Only 20% of staff accepting voluntary retirement may be replaced.
The indications are that up to 35% of senior level posts in Durban are vacant.