Uber taking more money than quoted

3x in a row Uber takes off more money than the original quote, when I query it the response is immediate - sorry, we fix it - and I am back to my original quoted fee. Yesterday's trip went without a glitch, no extra money taken. Today I return the same way, quoted R97 but they app says R137 at the end of the trip. Now when I try to query it, the message is that I cannot query it as I've had too many price changes already. I never agreed to a larger amount, not ONCE - they just reverse the original payment and then take off the larger amount. Ridiculous. The drivers have been superb (clean cars, safe driving, friendly) but I will look for alternative options in future. I rather pay more from the start than have to fight to get my money back when Uber charge more than what they quoted. Read through the reviews, it is a common thread in all the complaints.