B3 service - low circuit coolant replacement

[rudey]

My e250 w212 , 2011, blue efficiency is on 155,000 and due b3 service just rang Oxford Benz and they want £980 for service, i had the transmission fluid changed two weeks ago when the electrics went in the gearbox ( £980) and i changed the antI freeze about 2 years ago after replacing top hose... i can understand the the b service ( £330ish) but cant see why they want £380 for a low circuit coolant replacement ( its not the air conditioning circuit )... i asked the service chap what it is and he didnt know ...anyone shed any light on this