I used to have BTE NHS hearing aids myself so I completely understand your frustrations on feedback! It was something every hospital I used said there’s nothing we can do about it suffered 25 years with feedback it didn’t matter what style mould or hearing aid I could never hug anyone without them going nuts, couldn’t brush my hair or lean in to listen to something close without feedback or even move my head too fast. I found asking for absalutely no vents helped a tiny bit but not much, downside is the occlusion but i found I rarely notice it now…
I’m not berating the NHS at all like you said it’s a wonderful function but most NHS audiology units see feedback as something you have to “live” with past a certain leval of hearing loss in my experience and they say well it’s normal. My loss isn’t quite as profound as yours and I had that exact same issue…they couldn’t or wouldn’t take the time to fix that issue over 25 years I don’t think it’s a hearing aid issue it’s a programming issue within their budget allotment so they give whatever is “deemed suitable and available for a particular loss” and one due to time limits and budgets for that particular hospital
Any side problems often gets pushed to the back burner because their main objective is to make sure you can hear something even if it’s produces feedback/whistling their main goal is to just fulfill the need
to hear anything fixed beyond that is a bonus. Some audiologists really do work with you as best they can with their software I’ve had some amazing NHS audiologists and some really shitty ones too
They fail to realise it doesn’t just impact you, if other family members are complaining about whistling to you then it’s a problem. Maybe at the next appointment ask are these the only hearing aids that will suit my losses or is there another option, also ask for moulds that are solid I found skeleton ones were more prone to feedback than a solid mould.
IF they cannot accommodate you it may be worth trying another hospital if it’s in your catchment area but if the travel isn’t far they may only have 1 brand…i.e London back in the day it was Siemens in South Essex I had the option of oticon or Phonak tried both ultimately preferred oticon. Lincolnshire and Yorkshire it was just Oticon for me as the preferred choice they recommended. On wait times it seems normal to wait months sometimes several months between appointments and one of the drawbacks of the NHS. If possible ask to go on a cancellation wait list sometimes I’ve been able to get earlier appoints that way with the NHS audiology unit, doesn’t always work but sometimes I’ve got lucky.
I hate to say it but if you are still unsatisfied with your NHS hearing aids it may be worth venturing privately, my first set of privately brought hearing aids reduced me to happy tears. I’d complained of a lifetime of feedback my fitter assured me with the newer technology that could be prevented or stopped completely even with my severe losses. 5 years on 2 sets of hearing aids and I have had NO feedback except if the moulds slide out on a sweaty ear day. Or I take them out before I turn them off.
I wish you luck!