No free parking

I was informed that if I take my Woolworths till slip to the parking machine it will deduct my free parking. When I got to the machine, the signboard clearly stated this and that thereafter normal parking fees would apply. You would therefore assume that it gives you your free 1 1/2 hours parking and you are then required to pay the balance due, but this is not the case, if you are over the 1 1/2 hour time limit you pay the full parking fee applicable. Bad advertising from both Woolworths and Blue Route.