Left stranded

I made a booking through booking.com with City lodge Grandwest . Upon my arrival i was told that my booking was cancelled because apparently they were fully booked. I was left stranded because most places were fully booked. I ended up getting accommodation at the Collysum hotel for R3600 which was almost triple the amount of what i had paid at City lodge.

I then informed booking.com and I was told to send my proof of payment which i did. But i have not received my 50%efund to date.

Best regards