I used Janus taxi service by emailing to order in advance for collection at the airport, I wouldn't hesitate to recommend his company.

I used Janus taxi service by emailing to order in advance for collection at the airport (two times) and at the port to return to the airport when I left St Lucia.

The service was superb : 
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a. Plenty of reassuring comms by email confirming exact detail of pickup, price etc
b. Prompt service on all collections
c. Friendly service - driver chatting about island and providing relevant info
d. Complimentary water bottle when I first arrived which was much appreciated ! 
e. Much better value than if I had walked up to taxi rank in Rodney Bay

I wouldnt hesitate to recommend his company. 
Regards, Susan