Thanks Jack o'Clubs for your reply, not that I understand a word of what you wrote.
CONCATENATE ?? daren't look that word up in the dictionary, believe it's illegal in many states in America and fairly sure it's banned in Alberta.
Wouldn't you know it that after posting here and a couple of other sites I did this:
Open in Excel the txt ascii price data file, Wizard appears, Next, Next, Date/MYD (date format of file)/Finish
Select Date column, Format/Cells/Number/Custom and enter yyyy/mm/dd OK and hey presto, date format changed.