Hub seems to be overheating

Good morning 

my Hub3 has a permanent red light for last few days. It is warm/hot to the touch.

I have done the reset and this made no difference. I have restarted likewise. I have logged into the hub and run the diagnostics but these are only for network - it tells me to check the temperature without giving me any indication that this is a physical check or a diagnostic on the same tool.

The hub is working which is good but I'm really worried about its overheating and it breaking. It has been in the same position for years , not in direct sun, and the house is not hot generally.

Please advise how I can get a new replacement hub sent/installed.

Thank you! 

Catherine