CB security won't refund me due to a non working alarm system

CB security sold me an alarm system which stopped working within two months of installation. They say I must pay R350 for the technical personnel to come and see. One beam is malfuntioning since it has been installed and one is recently dead. One eye of the system is dead and the whole alarm system wont arm. CB security won't state their guarantee and warantee on the product. By the consumer protection act I am entitled for a full refund and CB security is ignoring my e- mails.