Do not use Coinbase! They have extremely poor service and will not support you if you ever encounter issues logging in. Instead, they will write a generic response to your ticket and immediately close it. If any major bank tried to pull this they would get buried in lawsuits.
Again, avoid this service at all costs. Forget their greedy 5% fees on deposits/withdrawals - it doesn't even matter if you can't get your BTC or USD back period. That's a 100% fee.
Coinbase is one of the most used crypto exchange for fiat to crypto and vice versa transactions,if you want to accuse them give some examples or proofs why you are saying that they are providing poor performance or you will be just ignored like a troll.