First off, well done for walking OP.
If more turned and walked when faced with B&S or limited services then perhaps Sergei and his cohorts would start to get the message.
It doesn't matter how you do it, I've walked from Romanians claiming to be Spanish / Italian or whatever and used the empty wallet routine purely because I didn't want to risk facing Sergei and his brothers. It's all about self preservation rather than bravado. On the other hand I've also made it quite clear with a few others why I wasn't staying and in one case had a bizarre argument with a prossie who decided she couldn't 'make sex' whilst stark bollock naked using her smart phone as a translator - all to get a refund.
The important thing is to report on UKP. That will do far more damage to Sergei's cons than anything else.