That would have made no difference, the issue was a lack of communication in the factory, not a language barrier between us.
The stairs they did install (which have traditional stringer) are extremely well made and expertly installed, very happy with them.
Looks like they're leaning to agree to pay for the work required so happy with that.
Anyway, we live in a globalised market economy, I'll buy local when the quality, price and service justify it.