Uber overcharges for card payments

It’s been two consecutive days where Uber is charging ridiculous amounts when I pay with a card. When I pay with cash, I always pay the estimated fare you get when you request. But when using a card they always deduct that estimated amount before your drip and now for two times, they deduct more money in the card many hours after the trip has ended. I’d like to know why this rule of “amount taken from the card is a temporary hold” doesn’t apply for cash payments? Yesterday I prepaid R185 for a trip and late at night they increased the same trip to R261, deducting that difference from my account. Today the trip was R42 and just now they charged me R63 for the same trip. This is **********. I’m so sick of it! So Uber having access to my account means they can just edit amounts as they wish and deduct as and when it suits them?