Has anyone had problems with Coinbase?

I have commented on a topic about my problem but I start with a new topic about the CoinBase Support.

One month ago I bought Bitcoin with Coinbase (big amount) and then I sent them to an external wallet of a trading and investments platform.
When they showed me the terms and conditions, I did not accept them so They sent me my Bitcoin back but They sent to the wallet from I sent them.

As you know, in Coinbase, the address from where you send and the address for receive are different, so I can see both hash of the transactions from wallet A to external wallet B and then external wallet B to wallet A. But I dont see the Bitcoin on my wallet.

I've been trying to contact the support team for 3 weeks, opening tickets and answering the automatic mails with the case number, but I don't receive any update.

It's very frustrating because I'm talking about a lot of money and I don't have a simple answer from the team.