Hi and thanks for your fast reply!
A records for rievtech.co.uk point to the server hosting xlogic-relay.co.uk and the rievtech domain is successfully set up as a parked domain on the xlogic-account. That all works great.
Also now I have your plugin installed if I access any of the pages direct using the rievtech URL it stays in the address bar e.g.: https://www.rievtech.co.uk/product-category/accessories-and-cables/
BUT when I try and go straight in to the home page via rievtech.co.uk, the URL changes to xlogic-relay.co.uk. That’s the bit I need to sort out.