I wanted to send $9 worth of bitcoin through my blockchain wallet and was shocked to be charged a $4 miner fee.  I adjusted it a bit using advanced send but was sceptical when the familiar message that it might not be confirmed popped up. I didn't want to risk that so i sent it.  It still took 21 hours to be confirmed and i raised a ticket when i discovered $0.04 was displayed  as miner fee while $13 was deducted for the whole transaction, meaning $4 was charged. Then why the display of $0.04?
I got an apology as reply and explanation that miner's fee are based on file size of the transaction among other factors and not on the actual value of transfer and the appropriate
 miner's fee are automatically included based on dynamic fee calculation.
I wasn't satisfied with the explanation and still could not figure out what went wrong. I have never encountered that since I've been sending through blockchain. I wish someone could really explain this.