I'm not sure of any vendors in the UK (I'm from the States!) but one thing I want to say too is that you may want to stay off the Chinese juice for a bit too - you do hear of bad things concerning Chinese juice every now and then. Just like you, I got a throat infection from a cartomizer-based disposable e-cig, and mine was entirely built and juiced in China, so to this day, I was never sure if it was the juice or carto. You may just have to build up the funds to go to a local vape shop and invest in whatever kit may at least work in the meantime for you - I've had to make do with buying disposables from gas stations because all my tanks tend to taste like silica and trigger asthma and coughs depending on how long I test with them, or based on how severe the taste is.
Some times you just FREAK ME OUT.
Every time you type something new it gets stranger.
If you are buying Branded Product, even Hangsen or Dekang from a reputable Distributer/vender/etc. chances will be EXTREMELY rare of getting even 1 bottle of liquid with an actual issue. You may or may not like what you bought, but that has nothing to do with anything quality wise.
Sounds to me like the Op has purchased some off brand or start up Companies e-liquid. Very doubtful the Boges are the issue. Cartos can occasionally be a little hit and miss, but rarely are they All or nothing.
Maybe the dealer found he had been conned and got a real deal on Knockoff product. Not to take a loss, turn them cheap and recover funds. You never know.
I have been purchasing Boge cartos from various trustworthy sources for over a year and never even had a non firing carto. Every one so far has worked flawlessly.