Some help -
1) Contact local Regional Sales Manager in your marketplace, or FAE.
2) Email factory email@example.com
3) Post a case
To create a technical case at Cypress -
“Create a Case”
You have to be registered on Cypress web site first.
It is regrettable to waste the chip
You say C28000 series can not buy, But
C28533 etc are still available.
And or C21xxx series also have capsense functions.
Be careful to exceed voltage power-supply.