An AMS-LHR-JFK-LHR-AMS cash ticket with the short-hauls in economy (K class) and the long-hauls in WT+ (T class) should have TFC of €311.78, according to ITA.
If the short-hauls are in economy (Y class) and the long-hauls in CW (J class), the TFC should be €441.78.
So the difference in TFC when you UuA ought to be €130.