Last week, the left earpiece of my Sennheiser IE300 earbuds malfunctioned. I contacted the authorized service center in my country. After some time, they informed me that they did not have IE300 in stock and offered to replace it with IE200. I declined their offer and insisted on either repairing my IE300 or receiving a new one. They argued that IE200 is an equivalent replacement for IE300, Sennheiser told they so. Is IE200 truly equivalent to IE300? What should I do?