Hificorp N1 City looking for reasons and excuses to not fixed my appliance whilst under warranty

I bought a sound system from Hificorp N1 city and it was defective within 6 months. Luckily I still had the slip as I had 12 month warranty to have repaired or replaced. I took it back to customer care and was booked as a repair request. After 11 days I get a call back from HiFi corp accusing me of tampering with the appliance and claim is rejected. They are getting a call from consumer goods and ombudsman soon as I immediately lodge a complaint.