So many people seem to suffer from this when hypo that I thought I'd share my solution. After spending 6 months on antibiotics prescribed by my ENT the infection simply returned. I was signed off as hopeless but as I opened the door to leave he said 'Have you tried a neti pot?' Well that was the beginning of the solution. Neti pots using special neti salt are used to wash out the sinuses. I believe in some cultures/religions it forms part of the normal cleanliness. It worked. I upgraded to a battery driven and more easily operated Sinugator that I obtained from NeilMed. I rarely have an infection now - if I begin to feel blocked I rinse.
I believe these can be obtained from Boots as well