worst service

i booked a stay for the weekend at Masingita towers via booking.com and the booking.com app allowed me to book and pay and later on the day i was told by Sherriff from Masignita that the place i booked is already taken and that i should cancel and get a refund and when i cancelled i bieng told i will recieve my refund 7 to 12 days ..how does that make sense?how can i book an other place without my refund