after lots of dead ends, I can provide the following info:
Mascom does provide GPRS in Botswana. (www.mascom.bw)
The rates are between P10/MB (pay as you surf prepaid peak hours) down to
P 1.50/MB (Contract 500MB bundle).
Don't count on being able to be assisted by their help line. GPRS is an almost unknown entity to them. My guess is that few people are actually using it.
Try contacting them before you go to get the required settings for you phone.
Best of luck - you will need it!
On the other hand - I find that their voice services are very reliable and the voice support lines work excellent. Usually one is connected to a capable operator within 10 seconds.