Misleading size and return information

I recently purchased an item with a R250 voucher from Zando. Upon receiving it the jacket was approximately 2-3 sizes larger than advertised (and I did consult the size list before purchasing). Upon calling the customer call centre to enquire on the returns I heard that I now have to return the product, then wait for the money in my account and then order it again as I cannot just exchange it for a smaller size. With this process I will forfeit my voucher & now have to buy the item again but with full price. Had the advertising of the product (size-wise) been correct this would not have happened and I would be a very happy customer. I fail to see why there is a size chart if the sizes are so horribly wrong. Should this not be looked at per item? Clearer return indications will also be much preferred and time allowed by the courier so I can try the item on...this however I am informed of as well is the case where the courier bringing the parcel is not the person who is supposed to collect it again. Tiresome, poor service on Zando's part