Nedbank ATM *****s

Yesterday at Windmill in East London, went to withdraw R400 at Nedbank atm (atm***0v813) on the 28 Aug 2020 at 14:21 using my fnb card, only received R370, luckily I checked because it look right, 2xR100, 1xR50 and 6xR20 notes, I even took a picture. I called my bank FNB, they cannot assist and advised me to go to the Nedbank office. Why did I get R30 short of the amount withdrew? Even my in contact message confirmed R400 withdrawal. I am very disappointed with this to say the least.