Most unprofessional services ever

On the 26th of August this year my family and I booked online on booking.com for accommodation it was for a family trip we were planning in October for my birthday the place we boked at was Summerstrand Boutique Beach Apartments our booking was confirmed and payment was made on the 21 September with no issues on the booking.com website, our booking dates were check-in 27th October and check-out 29th October, on the 24th October I received an email from the host at Summerstrand Boutique Beach Apartment, thanking me for my booking and looking forward to welcoming me and hosting us and requesting a copy of my ID so as to provide us with further check-in details which I provided, a few minutes later I received an email back from them stating that just looking at the number of people who will be at the apartment am I aware of the number of bedrooms which was 2 bedrooms with 2 beds and there was a small sponge and a couch (we were 4 Adults and 2 children) I then rep**** yes hence I confirmed before booking and thy excepted my booking in August already with that same number of people. A few minutes later after sending my email I received an email back stating "Unfortunately we will have to cancel this booking, the excuse was that they have had issues with people booking as large groups of 5 and more and then complain about the comfort and facilities and they went on to say the apartment was meant for 4 adults and 1 child ( which never came up when we made the booking in August) they then continued to mention how it costs them more to accommodate large groups of 6 in terms of water and electricity (which was also not mentioned as a factor when we made and paid for our booking months in advance) with only 2 days left before our trip ( tickets already booked none refundable)we were forced to look for alternative last minute accommodation out of pocket because their refund only reflected in our bank on the 28th October, they were unprofessional, rude and I would never ever make a booking at the Summerstrand Boutique Beach Apartment ( booking made from booking.com).