Obtaining Angola work permit

Hi, Does anyone have an idea how best to approach applying for work permit in Angola. Employee is a French citizen currently living in Paris, and will travel alone (no family). We understand a few basic facts ie, application must be made through Angola's embassy in Paris and also that the embassy then sends the documentation to Luanda for the relevant government department to approve. My questions are: 1) for the government approval to be obtained in Luanda, do we need a local visa agent/company to monitor the process. If so: 2) How much should we expect tO pay for their service; and finally 3) Can anyone recommendations Luanda-based visa companies who might be able to help. Thanks