I was treated for this 6 times, the last attempt finally worked. I'm allergic to penicillin so had Clarithromycin, omeprazole and metronidazol, first course one week then same again for 2 weeks, third attempt the same, as was the forth, except they changed the PPI. Fifth attempt they added bismuth (fortunately they don't make anymore), it was awful. Sixth attempt, the antibiotic was levofloxacin (sp), the course was bad as I got most of the side effects from this hideous antibio. However, it finally worked. I had to have 3 test to be convinced.
Good luck.