I booked through Agoda.com

My partner and I booked an apartment for the 27th till the 29th. Today I received an emergency call that I need to be at Eastern Cape by friday. I called the 1st Albert Building apartment to request for a change of dates (reschedule), lady who picked up the phone told me my request was impossible so it's either we come check in on the dates or we lose, then I asked to speak with the manager she refused, asked for an email address still she refused and hanged up the phone