I've have not yet come across a very good solution to this. Any help
would be very much appreciated.

I need a macro that is able to iterate through the rows of my data and
then for each row it iterates through takes two pieces of data from
columns of that row (eg: Company and City). It then finds other rows
containing the same data for both Company and City and combines the
data of these rows into only one row.

Here's a representation of my problem:

Befo
After:

Company: City: Address: -------
Company: City: Address:
Company1 City1 444 Broadway
Company1 City1 444 Broadway
Company2 City2
Company2 City2 333 Milburry
Company2 City2 333 Milburry
Company3 City3 111 West
Company1 City1
Company1 City4 666 East
Company3 City3 111 West
Company1 City4 666 East

Thanks in advance to anyone that helps.