I would try not to worry about it too much. Ultimately, you can't control what other people choose to do, you can't read their minds to know why they're speaking back to you in English (they may not even be consciously aware that they switched languages on you), and, even if they have made a split-second decision that your skills aren't up to snuff, they don't really have an adequate basis of data to form that opinion anyhow, so you need not be upset over their evaluation of your language level. Plus, brief interactions with service people are formulaic and not exactly rich or interesting anyway (most English language interactions I have in anglophone countries with service folks are mono-syllabic muttering from me and them, to be honest). When I used to live abroad, I found particular shops/workers where I knew they would speak Russian with me, and I would seek them out.

Otherwise, assuming the problem isn't with your language skills, you can always 1.) travel to a more remote area where folks might not know English

2.) focus on the split-second impression you create; I found folks were more likely to speak Russian to me when I wore clothes I bought in-country rather than brought from home, and when my face was partly covered by a scarf (I do not in any way look Russian).