Hoolding bond to ransom over some weeds

My daughter has moved out of her rental and the real esate is being ridiculous with their exit demands. The yards were to be left clean and tidy which they were, but apparently not good enough, too many weeds left in the gardens, fair enough so we completly dug up all the weeds (has been raining here a fair bit) and some were pretty long term weeds, had trunks the size of small trees,they took four days to inspect after notifying them the yard was now done and of course with the weather some weeds had grown back, now they are holding her bond to ransom because of this. How can they justify this?