I pick out the words, '' As our commitment to loyal customers'' maybe nothing but I think it implies a tier system, of benefits, not just three holidays, but regular customers, if you go each year or twice a year you could get more benefits, and if you do not go for a year or so you might loose some.
Like a loyalty card, and a further push away from high street TA's trying to get more people to book online and direct.
Another option is TCD are hitting them and headline brouchure rates might need to fall, people want a straigh comparision, therefore they have to cut the 10% discount down.