I read that the Op got completely the wrong idea, and the provided p+c option to buy 10k points for $70 in his mind became to him,
'buy night for 10k from own balance and pay $70 at the hotel'
(not 15k + 10k p+c = 25k needed for chosen HI hotel )

I guess ops reference to a previous booking would be to a different cheaper on points hotel, or hotel booked before January devaluation.

Anyway p+c does not work that way, never has, is very clearly and unambiguously worded.

As for complaining about spending $210 on 30k points, what is the difference when op was prepared to instead hand over $210 at checkin. Basically that is same result, $210 less in pocket, and same points balance in ihg account. Let alone p+c is cheapest way to obtain points.