I ran the query through the Index Tuning Wizard and added the following index and this has fixed the issue:

CREATE NONCLUSTERED INDEX [tar_downloads_new3]

ON [dbo].[tar_downloads_new] ([tar_booked] ASC,

[tar_fileno] ASC,

[tar_suboperator]...

Hi Jack

Thanks for replying.

I ran the updated query, however, it is still taking an age to run for the 16th - 28th Feb but not for the 1st - 28th...