Hi Paul,
This one might be a bit tricky to describe in text but I'll go for it,
BACK UP THE DATABASE!
Make a list which contains only the two companies you wish to merge,
Drag the companie which you wish to merge into the other company on to the other company. That is to say drag the company that will be deleted to the company you wish to keep.
A dialog box will appear, choose the merge selected entries option its the centre one I think.
Delete the entry that you dragged onto the other entry.
I hope that made sense for you, If not post back and we'll try again.
Regards
Nick Welburn
CABC Support Manager