take loads of pics of the stuff and make sure you keep a record of when and wehre you bought it, the recipt numbers etc and the package numbers as well

just in case

if you want to be really horrible, write to the sun or soemthing but let the store deal with it, they'll probably get money from the supplier/producer which they'll either pass on to you or split with you

but how much is enough?
this ain't america you know