The actual purchase was easy and straight forward, but that's where the good news ended.
Firstly my purchase was held for security checking. After a very long wait and an email to customer services, my purchase was eventually approved and I received an email to let me know I could proceed. But I couldn't now my account, which was previously OK was blocked for "security reasons ". Another email to customer services wasn't answered until the following day.
So my "instant download " took 2 days!