Motivo Certo - Caução não devolvida em totalidade

CAUCAO DO ALUGAMENTO NAO DEVOLVIDA EM TOTALIDADE

My partner and I rent a flat in Sintra Mem-Martins from 1st of march to 30th of september 2018. As I am French and do not have Fiadores in Portugal, the landlord asked to give 6 months rent in advance. Two to pay for the first and last month (800 euros), and 4 months of deposit (1600 euros). The agency, Motivo Certo, did not do a state of the apartment when I enter and let the landlord's brother doing his own inspection without informing me or my partner when we left. I did mention a kitchen door which fell due to a leaking in the kitchen that we tempt to fix in march cf picture (landlord's brother and agency aware) when we enter in march. In september the door fell by it self as the door where damage by the water and I did notice it to the agency when we left. The door fell few days before we had to give the key. The agency did not wanted to be responsible for this and asked me to deal with the landlord straight away by e mail who did not wanted to give the deposit in one time at first, and then decided to keep 300 euros without any proof of receipt of the work he did. He rudely told me he will replace the whole kitchen (e-mails attached) to not having further problems with people like me. I have no proof of any invoice just an estimation of the work price on a piece of paper.
I was not here to do the inspection as it should of been done by the agency and myself or partner when we left, and there is no state of the apartment to proof that the kitchen was already old and the leaking was there when we enter. The agency denied any responsibilities and was useless as they did not do their work porperly and let me deal with it on my own, and a 300 euros were taken from me for no apparent reason neither proof. As I said we are not responsible for the damage as the kitchen was old and that does not justify a whole kitchen replacement anyway.
Here you will find attached my correspondances with the Landlord, Vitor the estate agent, and the landlord brother who was the builder apparently. I never met the landlord as he lives in the UK and we dealt only with the agency or the landlord brother.