Weirdly difficult to pay

I don't mind Lancet Lab in general, but account handling feels pretty abysmal. I've had SMS's sent demanding payment for (I'm expecting entirely legitimate) bills. No statement included, just "hey pay us, here are our bank details". That's not great.

I really hate owing people money and take quite a bit of pride in having a decent credit record etc, so money demands are serious business. However, I'd really really like to know what it is I'm paying for.

After many emails back and forth with ***, I managed to get to the bottom of (and a statement for) one of the payments required. Another is outstanding and I've received many demand SMS's to this effect. Despite attempting to find what this bill is for, my queries have gone either unanswered or have just been met with confusion for the past month, just about.

Today I received a call asking for payment, so at least over the phone I requested some sort of statement or invoice. The caller said this would be done and arrive shortly - it's been just over an hour and absolutely nothing, except for a transactional SMS confirming my settlement arrangement with a deadline of tomorrow.

If tomorrow comes and I still don't know what I'm paying for, I don't think I'm likely to pay blindly for it. Weirdly. As I understand it, general good-practice (though I'm no expert) is to include a statement or invoice, or at least some sort of breakdown or detail whatsoever, when payment is required. That's all I'm asking for - I don't need payment breaks or expect any leeway particularly, I just really really want to know what I'm paying for. Please. :D