BTC and all special meals (veg, kosher etc.) should be able to transfer over to the new flight (the meal requests, not the actual meals, just to be sure ). Physical menus should be able to pick up in SIN as they would be distributed on the regular SQ326 operating that day anyways and it shouldn't be that there is only one set of menus to go around.

Being taken to a Y counter to get the cab reimbursed wouldn't be the end of the world to me, but for true F / Suites experience maybe the staff could have resolved it amongst themselves and then the money would have been paid to the guest at the F check in area (the staff from Y ticket desk or so could have popped over).

Certainly some room to improve the experience.