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.
I have known this company for a long time and they have never disappointed me, I dont know the issue you are having with them , but has not really affected majority of people, your experience with them might be a bitter one, but it is not enough to pull the crowd along in your decision.
What if it was just a simple technical issue, we dont even have the details of your real challenge for us to follow your advice, the only challenge you have mentioned here is your mail not being attended to, maybe you should push a little further, Facebook once did something of such to me because of many client on queue for them to attend to, but I had to push a little bit more till the resolved my issue.
If I wasnt patient then, I would have probably come on one of these threads to tarnish their image.