Edgars not transparent or honet in communication

Upon making a purchase at Edgars, I requested the teller to ensure my purchase was put on the 6 month no interest plan, which she ensured me it was. I have now recevied an account noting the amount was put on an interest plan. Upon phoning Edgars it was explained that only purchases over R600 qualify for interest free. I then requested how I could pay off the full amount immediately in order to not incur further interest, I was told this is impossible! All payments would be spread over all plans! There was no transparent or honest communication at the till point and I am being prevented from settling this amount in full, which is ********* and manipulation of customers fund. I WILL NOT BE SHOPPING AT EDGARS AGAIN! very disgusted in this service and sly financial policy.