个人认为：1.action改成behavior更为妥当；2.before I paid the last rent改成before the last time I paid the rent.因为你的说法容易混淆，the last rent可以译为“上一次交租”；3.I have already told the landlord very clearly that I would stay 3 more weeks. She asked me to pay the 4-week rent as usual, and would give one -week rent back to me in the end.

其实你翻译的已经算很到位了。