Faliure to reverse funds due to a technicality

I have been a loyal customer at Sto-Rage Constantia Kloof since May2015.I have moved homes and did not need my storage unit anymore.I advised Sto-Rage SA on 22 Feb 2016 that I will be terminating my contract in the agreed month in advance and received a response on the day that I need to have my valuables removed, storage unit cleaned and lock taken off by the last day of Feb. On 29th Feb I emailed Storage SA advising that I have cleaned out my unit and will on that afternoon remove the lock and thanked them for their serivce. Being only human it slipped my mind and I made it a point to go through the very next day (1 Feb) and removed the lock and personally went into their offices to advise of such. I was still debited for the month and was told by Takalani that he will have to ask headoffice what can be done and he will get back to me, he never did! I ff'd up on 8 March and was told I will not get my money back. How is it fair to make a loyal customer pay for something he is not using. Why not take the funds for the extra 1 day and refund whats due to me. I was told that this is impossible. I feel cheated over a technicality!!! >Throw away a loyal customer over R760????