ONOMO Hotel Cape Town - Inn On The Square poor booking service and number phone doesn't work

Hi made a booking for December and I've since tried to call the property to make changes for my booking but this phone number: *** is just useless and the phone isn't answered, I've a booking through booking.com who also can't get hold the hotel number. I have been frustrated and I have now cancelled the booking and I see that the cancellation fee is to the value of the booking fee - this is unacceptable and poor booking service from this hotel. My booking confirmation number is: ***