This might not help you, but I had urinary problems for years and they'd end up causing utis and I ended up with a kidney infection too.
I did loads of research and listened to what others wrote on here and came to the conclusion that I was suffering from interstitial cystitis. I learned how to control it by restricting the type of fluid I was drinking and the symptoms massively improved and the infections stopped.
From what others said, many women have a permanent bacterial film embedded in their bladder lining which will grow depending upon conditions within the bladder. It can be treated by accessing specialist care (usually private consultant for IC) and taking weeks, if not months of antibiotics following identification of the type of bacteria present.
I control mine by avoiding tea, instant coffee, fruit juice, fizzy drinks, alcohol and anything citrus. These are my triggers. The tea and citrus are the worst triggers. I slipped up at Christmas by eating some tangerines. I started with cystitis then the urine started smelling. I dealt with it by taking the uva ursi for five days and it cleared up. I can't afford private investigations or treatment so control is all I can do.
Your bacteria might be persistent, but treatable by the NHS, but if not, see what you think about controlling the bacteria by other means. Some people also take D mannose as well. Cut out all your fluids and drink only Evian water for a week then stick to low irritation fluids like water, milk, herbal teas, redbush tea and see how you get on. Cut out tomatoes and citrus too.
They have to remove your coil if you demand it. Tell them you no longer consent to having it inside you. Some women remove their own, but you might not be willing or able to do that, which is fine of course.
This info may or may not help, but I don't know where I'd be now without this advice from the people on the health boards here, years ago.