Store Manageress screaming at customer in front of other customers

On the 3rd of November I lodged the 4th complaint that the ADSL line is running at 25% speed on my 3 month old contract. No technician was dispatched. On the 12th November the line was dead. On the 16th November a technician finally came out after escalating the issue. He informed the router was faulty. We went to Clearwater Telkom on the 17th November and after haggling and begging we finally got a new router. Still nothing. After further begging a technician finally came out again, tested with his router and confirmed that the line worked. Once again he told us to go back to the Clearwater store and exchange the new unit as it is faulty. Today 21st returned to the Clearwater store only to have the store manageress screaming at us in front of the other customers that they will not exchange the unit, even though it is within 7 days and their own technician says it is faulty. The shop manageress refused to pick up her phone or answer the email sent by her Head Office while we waited in store for the issue to be resolved. She was obnoxious , treated us very badly, throwing her weight around , creating a spectacle in front of everyone in the store. This was both extremely embarrassing and unacceptable behavior. She does not even have respect for her own Management at her Head Office in PTA , refusing to pick up her calls, knowing full well that they were trying to contact her to advise her to exchange the unit. I will take this up further with higher management and the consumer protection act. What kind of caliber management does Telkom employ? This lady is a disgrace to the customer service sector of our Country. I for one will not let her get away with treating us as 2nd class customers and insist that she is dealt with accordingly.