Merged left hand column prevents sorting data

Hi there,
I receive sales figures that look something similar to the following


The problem is that I cannot sort the data because the the rows in the left hand column for each area are merged. Obviously I could unmerge and fill down each area name but I've got rows and rows of results so that's not an ideal solution. Any suggestions for a quick work around?

Thanks,

Natalie

(Data attached - pasting isn't working very wel!)