Macro to convert data in cells into time and caculate number of hours (Nice challenge this one!)

[tonywatsonhelp]

Hi everyone,,
I've got one to get your brains thinking,
Ok so I've got a sheet and it has times in it (Its a record of peoples working week and the hours they have done)

the way the data is collected is simply as data, it has little or no reflection on a time, I need to work out the number of hours worked.
so here is what I need,

Columns B,C,D,E,F,G,H currently have the hours worked have the hours worked l need to take the data, translate it into a time frame and calculate the hours for each of those cells, I have no problem with columns being added to make the data calculate out
Currently a column looks like this:

9:00a - 4:00p

5:00p - 8:00p

7:00a - 4:00p

5:30a - 2:00p

3:00p - wed 12:00a

<COLGROUP><COL style="WIDTH: 86pt; mso-width-source: userset; mso-width-alt: 3680" width=115><TBODY>
</TBODY>

as you can see it has all sorts of problems including "wed" in the way.
any ideas how I can get this to work?
the result I want is one cell start time, the next cell end time the next cell how many hour's worked

thanks

Tony