Very Poor Service

i have ordered something on the 31 mar 2015 which was meant to be delivered on 1 april 2015. however this is still in transit and iv now been told that it will be delivered on the 7 apr 2015 which is not acceptable as i have paid the fee for overnight delivery. this is not the 1st time that this has happened, now my production will stop over this weekend. very very bad service!!!