1) Go to Reports > Customer List
2) Untick 'Search by Visit Date' - this allows you to search all your customers
3) Enter the customers details in one of the fields (i.e. surname, mobile, email)
4) Press 'Get List' which will show you all the customer that fall under your search
5) Tick the boxes of the customers you would like to merge:
6) in the With Selected Drop Down - select 'Merge' and then Go
7) By clicking on the customers information it will then populate the top line to the "master" profile
8) Click 'Merge' and voila! 3 become 1!