Faulty devices

I placed my third order on the 25 May only after many phone calls did I receive the order on the 5 June. the device does not work I immediately contacted your company and was advised yhat they would send a exchange after I sent evidence that the device was in working order. I am currently still waiting for the replacement device and the faulty device still hasnt been picked up 8 days later. everytime I ask I get told today.