If your Buys are Disabled by the Assholios at Coinbase then you cannot Log into GDAX or make any purchases.
CEX.io actually cares about their customers and responds if they have an issue. https://cex.io/r/0/up107988344/0/
You can tell GDAX customer service has the same email system that Coinbase uses even though they are little better in responding to issues GDAX Is Coinbase in terms of the functionality and service a person receives.
https://steemit.com/coinbase/@zackcovell/toxic-coinbase