Okay do you have this motor and experience the same issue? It began only after few months of use.
Yes, I have this motor on 4 bikes that i look after (mine and 3 friends)
As
@Peddlin' Pedro said above
You'd be amazed how many times someone's been adamant their BB is creaking and it turned out to be something completely different.
My first instal was on my own bike, a Dawes Super Galaxy and like you I experienced what sounded like a squeek from the BB area when pedalling - it drove me nuts.
Now, I've been maintaining and building my own bikes for several decades, but the squeek took a while to track down (and I won't bore you with all the things I tried).
Squeek One - the headset bearing needed re-greasing - yes, nothing to do with the BB but it had all the symptoms of coming from the BB as that is where it seemed the sound was coming from and only occured under peddle pressure (when of course you're pulling on the handlebars)
Things were ok for a while, then, oh no, another squeek from the BB!
Squeek Two - another long story short - the Dawes frame is what's known as a lugged frame and where the TSDZ2 Bridge Plate secures the motor against the chain stays was the problem in that the Bridge Plate was not siting squarely on the frame lug. On dismantling I could see bare metal where the plate was wearing away the lug. Repositioning the Bridge Plate solved the problem for a while but I never did entirely eliminate this re-occuring problem. The motor is now on a non-lugged frame.
So two squeeks that sounded like the motor in the BB, but they weren't.
Finally,
1. the cranks need tightening to 40nm which is way tighter than you might think (I bought a torque wrench and realised that even after having worked on bikes for a long time. I was suprised that my guess at 40nm was a long way off)
2. The lock ring - just by using the supplied tool with hand pressure is not enough - after hand tightening I tapped the tool with a mallet to get a bit more torque to something like the 40nm required on this piece too.
OK, so for some reason your motor may have a defect in which case you've been unlucky, but with 4 motors installed (and more than 5,000Km on my own), I've not had any undue problems.
The pics below are possibly from the Woosh manual for the TSDZ2 installation -a company whom I'd recommend for their excellent customer support and documentation.