I've had really mixed experiences with support from them, ranging from this to awesome. Mostly it's been ok - except for their more legacy products. Sucks you wasted your time, but I'm glad it's fixed!
While stock service support is good (EC2, S3, etc), we've had terrible support with Elastic Transcoder. 1 week+ on an issue that completely breaks HLS video encoding. We switched to encoding.com because I get to talk to a human being, over the phone, and aren't put through a support forum.