Nick,
Section 75 of the CCA is a long and arduous process to follow, I previously used it when a flying club went under and I had to reclaim 1000 pounds from my account. They do seem to expect you to provide proof that you've persued all over means to reclaim the money.
In the situation with Etihad, they did continuously promise to refund the money on several occasions, and always agreed that it could be refunded as it was a fully refundable ticket. It was simply a slow process, but had it taken any longer, then we would have used section 75.
Singapore Airlines on the other hand, when I've needed to cancel a fully refundable ticket have allowed this to be done online and refunded it within 2 days.