I feel your pain! I went through a-fib for 14 years. Had 3 ablations, more cardioversions than I can count, and felt like you do. Had to work, always exhausted, etc. After the 2nd and 3rd ablations made things worse, I insisted on a second opinion medically. MY ONE regret is that I didn't do this sooner. As I'm sure you know, when you have this going on all the time, you aren't thinking much further than getting through the next episode.
I was referred to a cardiothoracic surgeon who worked with my electrophysiologist cardiologist.
I had a bilateral thorascopic surgery, similar to 5-box on December 12, 2012. My 2 weeks off work turned into 7 weeks as I developed pneumonia and was very very ill. However, since my recovery, I have only had one minor episode (45 minutes and it self-converted) of a-fib. This was at 17 months. I am now 21 months with only this one small "blip" on the screen.
I continue to be mindful: no caffeine, limited chocolate, watch the sodium, stay hydrated, and take a diuretic once a week. I exercise regularly 4-5 x a week, eat healthier than ever, and feel like I've been given a second chance at a good life. My job is highly stressful (I work with mentally ill heroin addicts on methadone) so I have reduced my hours to 32 per week. My "blip" happened during a particularly stressful time at work when my hours had crept up to 38 per week).
I really encourage you to find a cardiologist who takes your condition seriously. It is always okay to get a second opinion. I'm not sure where you live, but there are many fine clinics available, and it is well worth seeking out the best care you can find. As I said, my one regret is not getting a second opinion sooner. GO for it! There can be life after a-fib.
Sending prayers and hugs for you to have peace and health soon,
MaryLL
p.s., there's a new procedure in the US called a 5 box mini maze. It has shown some promise for persistent AF. I'm guessing you're int he UK, not sure if they're doing the procedure there.
If the problem is rate control, I wonder if it's time to do an AV node ablation and go to permanent pacemaker.