That you dialled *599*10# & got credited with bonus of 6000 mins was an error from the network, MTN said...
This is the new campaign called Wake Up Offer where specific customers are to opt in and enjoy 100 free minutes to call a special MTN number, which is randomly selected from their frequent called numbers.
Eligible customers will be randomly selected by the MTN's Marketing Team.
Eligible (active) customers will receive an SMS notifying them of the offer, and are expected to send FRIEND to 400 to receive the special number.
The free minutes received will be used to call ONLY the specified MTN Number in the message received and not any other MTN number.
Eligible customers will be able to check her/his bonus minutes by dialing the USSD code *559*10#.