Cancelled booking on WhatsApp

We booked a table 3 weeks in advance for 12 adults & 3 kids - Sunday lunch for a birthday party. I visited them on Saturday afternoon to have a look at the venue and confirm with the manager that all was OK. My booking was for 12h00 on Sunday. 9h30 a Whatsapp was sent to inform me the the staff was 'overworked' due to the Saturday function and that they cancelled the booking. Not even the decency to give me a call - just a Whatsapp with a lame apology! According to friends I am not the first one to receive this treatment. They will never see me again!!