Denon Service Delay and no proper contact to talk directly

[Sarihaddu]

Hi everyone. I am Suresh. After struggling a lot and saving enough, I purchased Denon AVR S760H in 2022 October. Its subwoofer preouts stopped working. I travelled to service centre 350 km away and submitted it on 30th Aug. After 1 week, SC guy told motherboad fault and needs replacement. I have waited and when I called him today, 19th Sep, he is saying "Head office has no stock, I don't know when it will come to me, you call head office and tell them to send me motherboad". Does Denon really take so long to repair something in this day and age? What else can I do to elevate the issue to make them look into the matter?

Thanks.