I have worn hearing aids for several years. Always through the Audiology Department of my local NHS Trust. I need them in both ears, and cannot fault the care that the NHS takes with these. Unless I tell people no-one even knows I am wearing these, just a small box sits behind each ear. Plastic tube going into ear. These tubes do need replacing about every six - nine months and this is done by the NHS at the Audiology department. No appointment, just go along and take a numbered ticket and wait my turn. All the batteries are also supplied without charge, and I can get these at a local clinic and always ensure I have a goodly few in stock at home and in my handbag.
I have never understood those who pay out so much money for hearing aids. If they really need them, then the NHS will supply and service them. There have been a couple of occasions when one has got lost (this last winter, one must have got pulled out when I was all wound up in scarves, etc, during the cold spell), this was replaced without further charge. Wonderful service.