Help..Disturbing the peace???

We need your urgent advice. One of our second floor corner unit tenant seems to have decided to stay up all night and sleep during the day. This tenant  walks with heels on ceramic tile floors back and forth  at all hours of the night keeping the owner below awake.. The board tried to resolve this issue by talking to this tenant and having the complainant explain to this upper unit owner the noise it creates and how they have not slept soundly in the past month. The problem is the unit owner will not admit that he or she is making excessive noise.  What are our options to solve this situation? Your advice in this matter would be most appreciated. Thank you.