Yes, the Supreme Court has declared the 5-6 lending scheme illegal, citing Article 1409 of the Civil Code. An agreement that allows for excessively high interest rates goes against what is considered right and fair, therefore may not be legally acceptable.
As for the Sangla-ATM scheme, it is not illegal per se, but the Bangko Sentral ng Pilipinas strongly advises borrowers against it due to potential implications of fraud and unauthorized withdrawals.