Bank Reconciliation with VBA

Xl genius I need your help!!!!!!
I have the attached xl file and I would like to make a reconciliation through all this transactions.
I would like to compare first, all “N” the “REF” column. If the find the same (one or more times) I would like to check the “M” column and make the total sum (of this reference) in order to “much” and make zero total.
As an example [ATTACH]378738
-10 REF2525
9 REF 2525
1 REF 2525
I want all the above transactions to exclude or to highlight this transactions.
After all this I would like to have all this transactions without munching in ref column and without the total sum of this sums zero

Thank a lot in advanced