Can someone please tell me what the minimum/maximum penalties in SA, ( Including any possible demerit points ) for the following..

The vehicle was followed, with only the driver within, into the private car park of a shopping centre, where they was asked to return to their vehicle and submit to a drug test which subsequently was determined to be positive.

There are no other extenuating circumstances, the driver was not speeding or in any other way driving erratically.

Thanks in advance