Hi replacement cooker now faulty, argos not helpful....

Hi Im Lynda and Im trying to find out where we stand with a faulty replacement cooker we have, I have phoned argos and said that we would like a replacement (it was purchased 29/08/07 and replaced 03/03/08) under the sale of goods act they are liable for 6yrs, the agreed and said that if we pay for an independent report and it proves it is a manufacturing fault we maybe able to have it sorted, the fault is the same one we had with the firat cooker and that was repaired 4 times before it was replaced, to be fair we cant afford to spend money on reports that may get us a replacement let alone replace the cooker, any help would be gratefully recieved, thanks for reading x