Hi. I am so stuck! So I sell second hand children’s clothes. I have started to buy clothes from my customers. I send bags with prepaid postage labels so all they have to do is fill them up and drop them off. I am finding a few people are ordering these bags and not using them so I have wasted my money. Any ideas where I can print off labels that I won’t be charged for until they are used? I have searched and searched! Thank you