Thanks both, useful info, any idea how they are collecting this data?
We could have a freelancer/contractor who used it, ultimately we'd never know and all our designers are home working these days anyway, or as above it could be an old device we disposed off despite it being scrubbed.
A thought did occur that we have had a bunch of new starters who came fresh from uni so they could have had student copies lying around that somehow got linked or one of then downloaded a 30 day demo with a company email address.
Regardless it seems rather daft to throw lawyers first rather than a polite 'you use our software already' call from sales (which I'm sure we'd have been receptive to) but what do I know...
Also regarding ignoring, is it worth us sending back a solid refutation of any evidence and then ignoring or just ignoring anything further?