EY UP Lisa,
as Baz say's depends what sort of problem your having???
I used to have the Tamron 70-300 with macro on it..with it being a zoom i suspect it will only be 1:2 which means it will only reproduce half life size a true macro is 1:1 which is lifesize.
Also it will have a set range for the macro the 70-300 was from about 190mm i seem to remember which means you have to be at least 1.9 metres away from your subject,and obviously would not focus past 3 metres (300mm).
Hope this helps if not give us a shout...
Mello.