Deleting Duplicates of Second Instance

Hi. This is my first time so please excuse my questions. I am still trying to understand how to attach and upload files here. The original file that I tried uploading is:

delete duplicates.jpg (I had no idea you were supposed to press upload so I kept exiting) I tried the paper clip but it just gives me a blank box. I don't know what to put in it.

I do a mass phone blast when I have to publicize a lecture that I am organizing. I have 3 columns. The first 2 columns (Column A and Column B) are exported from my contacts in outlook. It is their home phone and mobile phone. If they don't have a home phone or a cell phone, the cell is blank. I need these columns to stay as is.

It is the 3rd column (Column C) that I need to be edited because I add these numbers to the phone blast. These are the phone numbers of the people who call into the hotline. Some of them are members who are already in the contact list and some of them are not. Therefore I need the duplicates (the ones already in the outlook contacts) to be deleted from Column C only. Please note also that column C is in a different format because I copy and paste the called phone numbers straight from the hotline system's email into excel.

I have tried to run the macro but received an error as you will see here: (I hope)

compile error.jpg

Please advise.