Hi,

Unfortunately the agent in Qatar is correct - you should be charged 75GBP. I have looked up the fare rules for the "B" class UK --> Dubai fare and here is what I came up with.

From: London, England (LON-All Airports)
To: Dubai, United Arab Emirates (DXB-Dubayy Intl.)
(and return)
Fare Basis Code: BE6MGB1

PENALTIES - CANCEL-75.00 GBP BEFORE DEPART
CANCEL-75.00 GBP AFTER DEPART
CHANGE-75.00 GBP BEFORE/AFTER DEPART
FOR ALL CONDITIONS SEE TEXT RULE

I would try your luck with another office

Cheers