Storing mail over 24hrs before its being transported.

In Dec posted important documents on Friday morning but my mail left following Friday. Today wanted to post an application letter got there few minutes before 8 only to find out they open at 8.30 so my mail will only go the following day morning. Its gonna stay 24hrs at post office. Raised it they dont see anything wrong.yet post office at shoshanguve if u post before 11 it goes on the same day. Is it practical for mail to stay 24hrs before being transported.im finding service not working for customers. Person came to collect mail while I was waiting for them to open. Even in December samthing happened three days waiting to be shipped.had to go to other post office so I get the service I deserve yet town was the nearest from my work. Something needs to be done about this.im not happy nor impressed.