Just a note: September is months away. There is no need to buy train tickets that fare in advance. In fact, there is no need to buy tickets in advance at all.
That your ticket refund request was accepted indicates that it was a normal price ticket. (Supersaver tickets cannot be refunden). Those tickets are always available, and always the same price, wether bought a year or a second before departure.
So the best thing to do, to avoid such errors, is not to worry about getting mass transit tickets months in advance.