Broad Match is Ridiculous
the broad match is literally a joke,
the keyword Polytunnels triggers when searchers type:
there is broad then there is off the scale....
I'd suggest you not to use Broad match keywords except Broad match modified - just a general ppc tip there. Rather invest more time in your keyword research than having to use Broad match and get lots of irrelevant traffic.
We had an example this morning were '205 peugeot' appeared for a holiday/travel keyword.