No one has every advertised SystemCheats as undetectable, there isn't a cheat on the internet that is undetectable, not sure where you got this idea from.
Undetected and Undetectable are two very different things.

As far as payments go, you paid with a bank transfer, the wait time for this is entirely out of our control. You would need to pay with a credit or debit card if you want a instant payment to go through.
https://www.systemcheats.net/forum/s...3-payment-made