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.
Contact Vodafone on their 24-hour customer service phone number 0870 183 0612 / 0843 504 3747. 191: If you are an existing Vodafone customer and calling from your mobile, simply dial 191, which is a free number if you are calling from a phone with a Vodafone contract.