Unfair billing

Dear Peter, I'm a returning diplomat from a South African mission who bought a car and coming back with it from serving my country abroad. Now I'm told I have to pay R558 000-00 for customs and duties which I found it ridiculous and a reap off. I suspect AGS (removal and clearing company), SARS and some DIRCO (dept of international relations and Cooperations) transfer official are personally benefiting from the whole process. I'm saying this because AGS refuses that i should pay the amount directly to SARS instead they insist that I should deposit the money directly to their account or threatening me that if I don't in 3days, I will suffer the storage costs. Can you please investigate this process or returning diplomates and why this abnormal amount and whether SARS does receives or demand such payments and for what?