Have had a nasty experience recently when departing on SQ in Y from Jakarta (CGK): been denied a lounge access as *A Gold in direct violation of both *A official policy for contract lounges and explicit listing of the lounge in question (Esplanade T2) as accessible for me.
Written to their Twitter support, they have forwarded my complaint to Jakarta office, and I got an utter nonsense reply from their side. Forget compensation, not even an apology, they just backed up their ground staff ignorant and offensive behavior.

Thinking how to jump over alternatively gifted Indonesian office of SQ or, if unsuccessful, escalate to *A Global customer care.

BTW, does *A guarantee anything for the customer and can assist with enforcing its policies?

UPD. SQ moved from T2 (location of Esplanade) to T3 on Nov 28, 2018, after my flight took place.