Export history of several pairs in EXCEL, format and add to previous run

This request requires some Excel skills  and MT4. I know there are excel commands now in MT4 – so I’m hoping this is not too hardy.

I would have a folder with every pair on them (binary pair or std pair) for several timeframes.

Folder would have for instance EURUSD1.bo, eurusd5.bo, AUDUSD1. Format of date has to be changed with dd/mm/yyyy.

By running a script, I would like all these files to be updated (NOT replaced) with the latest data.

One run should update all my pre selected pairs. This preselection can be hardcoded in the script (i.e. I can go in th script and add new pairs if required).

Steps would be like (maybe):

1. Import excel for selected pairs and selected timeframes.

2. Change the date format to dd/mm/yyyy (making sure we have / not .)

3. Merge with existing pair in Excel folder (i.e. if I have the history up until 12/3/14 at 6:01 on a 1mn, the next load should merge to take over from 6:02 same day.

Existing files will be cumulative of previous runs. For instance, as my broker only leaves say 3 months, I now have 4 months of data as I started 1 month ago. Progressively I will have 1 year + data as I cumulate info.

In other words, by running a script on any pair, I should have all my history updated and added to previous runs.

I need the source.