Concerening arrival and flight through Class C airspace...

91.130(c)(1) Each person must establish two-way radio communications
with the ATC facility [...] providing air traffic services prior to
entering that airspace and thereafter maintain those
communications while within that airspace.

Note the use of "THE" in reference to the ATC facility to which one has
to talk. Does this mean THE specific ATC facility controlling the Class
C airspace? Or just the ATC facility providing services to you at the
time? In other words, if you blunder into Class C while talking to
Center on VFR advisories, either perhaps because they forgot to hand
you off or because you wandered off altitude and they didn't notice,
would you be ok, or would you be busted?