Well, maybe the spacers are not included, but that would depend on the amount of travel that it was sold with. 120: No spacers, 80: All the needed spacers should be in the fork. That would explain why you would need to buy parts... This is what the manual says:
<quote=Manual>In CORSA, MARATHON, 44 Micro TI, 44 LR, 44 RLO, 44 Micro Ti 29”, 44 TST2 29” and 55 CR you can change the fork travel with specific spacers which can be installed on fork, supplied in the box or sold separately.</quote>
I cannot find any service manual on their site, which is a shame. Apparently they indeed want to do travel changes at service centres. Too bad; with most fork brands it is not difficult to do yourself if you have the manual and the right oil/lubricants.