Lesson learnt: take post usage photos whilst parked in a layby/before handing keys back to rental staff.
The repairs cost us £300 of our deposit return. We would normally take photos of the vehicle before and after, though on this occasion I was unable too, as the young man who I returned the car too drove off straight away, as I thought he was getting in to reverse and park it. We only realised this once the car had been returned and we touched down back in the UK (they sent an email and photos). We used the car to drive to Ohrid and back only and it was whilst we were parked up getting food before our flight home that someone reversed into the back of us (a noticeable, but minimal dint). Upon arrival at the airport the staff behind the counter informed me that car insurance was attached to the bill already and there were no available adds on.
On their website there was no option to add car insurance, so after an email to them I was told this can be sorted in Skopje airport.
We chose Alamo as they were the best of a bad bunch.