US computer voice pronounces METRES as MEETREZ

Hi - Is there anyway of editing one of the lex /rex files so that I can program one of the US computer voices to correctly pronounce METRES when the language is set to UK English?

When language is set to UK English using a US computer voice it says "MEETREZ" instead of "METERS".

A workaround is to set the language to US English but then it speaks ROTARY versus ROUNDABOUT and HIGHWAY versus MOTORWAY.

I could just use UK Kate or Simon but prefer the voice of US Dave and Susan.

Any ideas?

See if things improve by using Explorer to rename cphoneme.dat (in the specific map folder) to cphoneme.old.

Just tried this but made no difference. Any other ideas?