The slow replies/poor support is also a common problem lol. I can only suggest to escalate your case number through their social media such as: reddit (https://www.reddit.com/r/CoinBase/) and twitter (https://twitter.com/CoinbaseSupport). Do be careful with scammers impersonating coinbase, they’re pretty rampant especially in the subreddit.

You may also try your luck in one of the live support from here: Coinbase Support contact information