A question for platinum blonde

Hi all, I presently use the Schwarzkopf blondme range, bleach powder & blondme toner Ice. I am platinum blonde.

I want to put some lowlights through my hair, and just order a cap. I presently have a bob style and I want to add Some warmth to diminish the platinum. Can any suggest any good colors?

I'd really like to stick with Schwarzkopf if possible, maybe the igora range. I don't want to go to dark, just give me a bit more warmth as I'm getting older and want to grow my hair, I just want to tone it down slightly, therefore giving me a new shade. 

PS: Also need something I can use 20 vol developer with too.

No suggestions at all?  *anyone*

*anyone* *anyone*

Thank you