Trying to subscribe/purchase for an old SWTOR Account

All instructions on how to link an old SWTOR account, or now the EA account, to Steam fail or cause additional chaos and confusion.

The reason I wanted to link SWTOR/EA to Steam was simply because I was told on the SWTOR purchase/subscription page that I should link my EA account to Steam in order to be able to make purchases or subscriptions, as this was the only way my account/purchase could be verified. 

To help with this, there is supposedly the option of contacting support by phone (in my case, Germany). However, I have not been able to do this so far. This is by far one of the biggest disappointments I have ever experienced with game providers.