help me save hours of my life

bare with me..I am not a experienced excel user so my terminology may be childlike

I have a report that I export into excel everyday. Several of the columns deal with time and I need to have a "total time spent" column so it is in h:mm:ss format. The problem is, not every cell has the "h" so it exports into just minutes and seconds like this-> :54:23

there are hundreds of numbers like this and everyday I run the report then I scroll down the columns adding the missing "0" before the :mm:ss so it will add correctly

Is there a formula or something I can do to get these zeros to populate automatically for me?

please and thanks!