Urber transaction

On the 16th of August my nephew requested an urber ride using my card by mistake and immediately cancelled which means urber was supposed to reverse the money immediately,but once I saw that the was an urber transaction in my account I immediately blocked my card thinking it is a **** because weeks before there was an urber transaction that from this day I don’t know where it came from and did not get any assistance from Fnb,so I think while I blocked my card urber tried reversing the money but couldn’t because the card was blocked. After knowing that it is my nephew I unblocked my card thinking I will get my money but still nothing, I did the transaction dispute thing and they are telling me that they will charge me R 157.00. Why can’t I just get my money back after unblocking my cards without going through all that?