Deposit not paid back unreasonably

We rented a lovely home in Pringle Bay from Baytown Holiday Accommodation, leaving everything in impeccable condition after a lovely weekend. The following day, I got an email, stating that the chair that was on the stoep was lying next to the side of the house broken, and R799 will be deducted from my deposit. I tried to explain that that was not how we left it, and with an open yard, anyone else could have entered the yard after we left, I cannot be held responsible for that. In good will, I even suggested that I would pay half, but with an open yard it at least has to be shared responsibility. Our cars were in the driveway, so it would mean we would have to reverse three cars before leaving, drag the chair onto the driveway, jump on it to break it, and then leave. Who would do that? It is quite ridiculous. In any case, they saw no reason, and didn't pay my full deposit back. Maybe this is how they make some extra money? What a sour ending to what was a great weekend.