If there is a return policy that was in effect at the time you purchased the goods, that policy must be honored so long as you complied with all your obligations under the return policy specifically and terms of sale more generally. (E.g. if the terms of sale were "not for resale" and you were aware of that, if you purchased for resale, that would be a violation and they may be able to avoid honoring the return.)A store can, going forward, probably ban you from shopping there if you are a reseller; a vendor is not obligated to sell to someone who, even in a small way or indirectly, competes with it.