Dissappointed

I have ordered a personalised backpack from Soapbox, their terms are that they will send be the designed sample first to approve before they proceed with branding the bag. I asked them to modify the branding only twice now im being told they will charge me extra for further changes ????!!!!! Is it not my right to pay for a product which im 100% happy with? Why do they even send a sample for approval if they then want to extra charge for the changes?