All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
What we understood from your question is that you deputized the company to send you the goods that you purchased from it by post. Therefore, the ruling on this company is the ruling of an authorized person [agent] and the agent guarantees the goods if he is negligent or abusive. It appears that the company is negligent by forgetting (to send you the goods) so it is obliged to guarantee the goods.
On the other hand, the company did not do the service which you entrusted it to do, so it is obliged to give you back the amount and it is not permissible for it to take this amount or to procrastinate in giving it back. If you cannot get back the money except by the method that you mentioned then this is permissible because it is permissible for a person to use tricks in order to get back his right even if he has to lie if there is no other alternative to get back his right as stated by the scholars . For more benefit, refer to Fatwa 88412.
Allaah Knows best.