I am not going to go into the details, but recently I needed to use 121.5. Quite apart from the original problem necessitating the call, I also developed a serious communication difficulty - I could hear them talking but it wasn't possible to hear what was being said. (And before some clever clogs decide that I must have had my radio turned down - I didn't) Eventually the radio problem lessened and I was able to hear an Emirates aircraft relaying messages to me. Communication with D&D was eventually restored too and my original problem sorted out. I am fortunate, I had had a visit to ScATCC a couple of years ago - well before I started learning to fly, but it was impressed on all there that we should always call sooner rather than later so I had no hesitation in calling when the need arose. For those of you tempted to turn your radios off 121.5 because you can't cope please think again. Without the help from that Emirates crew I would have had an even worse time of it.Thank you to all who helped me, I really do appreciate what you did.