As suggested, tell 'em to stick their "offer" where the sun don't shine ,then go forth and multiply.
Iwould need an extremely humble, grovelling apology from a school like that, before I would even consider further discussion with them, and i'd expect a "lower than ppl rate on the basis that, if i were qualified to CPL level, I'm already demonstrably more proficient than a PPL, therefore their job is easier!
I'd go out of my way to go elsewhere and tell them just why they are not getting my cash.....robbing barstewards!