That is the downside of generic ATMs such as Rediteller and GoCash. I withdrew $500 from a Rediteller ATM but only received $450. It took me about six weeks to be reimbursed the missing $50.
Compare that to the Commonwealth Bank. I left $300 in one of their ATMs and apparently after about 30 seconds, it goes back into the ATM if not retrieved. I rang the bank a few minutes later after realising my mistake, told them the ATM location and ID number, time and sequence number. My $300 was reimbursed in two business days. That is why I ALWAYS get a printed receipt with any ATM transaction. If no receipt can be printed, I go to another ATM.
Same as a friend who withdrew $500 from a generic ATM. Instead of dispensing ten $50 notes, she received $200. Whoever cashed up the ATM reversed the hoppers, hence the wrong amount. And it took her over two months to get her money back. Not good for a pensioner!