Sounds like this could have been handled much better by Emirates – although the aircraft change was probably un-avoidable but their communication (or lack thereof) after the event has been unfortunate.
They should ideally compensate you for the downgrade with a refund of ther fare difference between F and J and give you some miles as compensation given your loyalty.
I am not sure of your position or influence, but in my experience demanding to speak with senior management rarely gets results unless the incident was very serious (safety/health related) or involved serious negligence/ criminal behaviour.
A simple downgrade and bad follow up service is not something a VP would be interested in dealing with, no matter how high your status. If EK are likely to lose a multi-million dollar corporate account perhaps they’ll get a VP involved but anything less is unlikely – especially for an airline the size of Emirates.
I hope you get somewhere and are given reasonable compensation. Perhaps a clamly worded follow up to the above might help.
All the best!