Coinbase doesnt' take a 25% fee.  Ethereum has fallen in price. 

Also,  you should be able to look at the detail of your order with fees shown on coinbase without. 

If Ethereum had tripled in price you actually would have more in your account.

Coinbase buys it at the market rate that day using GDAX and then holds it until your funds clear.

So....I really think you are just mad.  Don't worry.  You are in good company.    I used GDAX to set buy limits to what I thought was as low as ETH would go weeks ago. and it hit yesterday....I was wrong. lol.  Now I'm on the losing end of the stick as well.

And don't use coinbase.  Use GDAX their trading platform.  You can login using your coinbase details. 


PT