I have a spreadsheet with data that represents mins and seconds i.e. 13:30 =
13 mins 30 seconds. When I try to total the column, Excel thinks 13
represents hours and resets when it gets to 24. I have tried to change the
format via Custom/special and time but nothing seems to work. I need to add
up the total number of minutes and seconds (this is a mobile phone bill!).

Hope someone can help, thank you in advance.

Cheers, T