I have a spreadsheet containing various columns of data

A B C D E F etc.
Agr no. Amount N/A N/A N/A N/A etc.

1 1 etc.
1 3
1 -1
7 2
8 4
8 -4
12 -13
12 13
12 13
12 -13
12 -7
13 2
17 4
18 1

The information in the other columns is not important, but I am looking for
a formula or macro that will automatically search for duplicates
(indefininate number of duplicates) in column A and and sum each 'AGR NO's'
corresponding values in column B and the put it on one line with all the
other information in the other columns also put to one line. The other
information in the other columns is the same for each of the duplicates.
Further if the sum of the duplicates is ZERO then it will just delete all the
information for the duplicates so they are completely removed. The page is up
to 10000 down so takes forever to manually source out duplicates.

The example above would ideally end up looking like,

A B C D E F etc.
Agr no. Amount N/A N/A N/A N/A etc.

1 3
7 2
12 -7
13 2
17 4
18 1

Sorry if this is a bit complex, but if anyone could help that would be
brilliant.

kind regards

Barry Walker