As to why they did nothing for two years, consider that they were told that there was no safety problem by both the manufacturer and the regulator, and they must have agreed, so why do anything? It's not as though pitot tubes are that expensive when compared to other costs. It was only after a few other incidents that they took action on their own to start the replacements.
Not so fast....Air France was well aware that the pitot tubes where a problem and sat on there hands. Yes, they had ordered them, but in hindsight too late. The fact that AF pilots refused to fly with the Thales pitot tubes after the accident because they were "aware of the problem" suggests that AF was not listening to there own pilots, or the pilots kept quiet...