A standard cooling fan is essentially a bladed DC motor. By varying the voltage input across the acceptable range for a fan, the speed of the fan will increase (to added voltage) and decrease (to reduced voltage); a faster fan means more air moved and thus a higher heat exchange rate.
Contact them toll-free from a Vodacom cellphone by dialing 111. Contact them toll-free from a Telkom phone by dialing 0800-111-234. Note: Telkom toll-free numbers are generally NOT toll-free when dialed from a MTN/Vodacom cellphone.
When I dial the customer service number for Verizon wireless (1-800-922-0204) from my Tracfone, I get a recording telling me to call a different # (1-800-353-1842). I am greeted by a recording thanking me for calling Tracfone. It goes downhill from there. I am a Verizon customer.