Return of new books

i bought books in 28December 2017. Titles are: The Merchant of Venice and Dancing in the Dust. The schools where my son is attending prescribed new books which automatically rendered the one's i bought useless. I could not return the books as i was in and out of hospital. Today when i visited the Protea Bookshop i was told they cannot accept nor are they obligated to take back the books because their stock "is not selling" therefore they won't refund me. The fact those book are selling should be an indication that are not being anymore is schools. Also the bad attitude service provider demonstrated was unacceptable as showed no interest of resolving my query and rejected my reasons of why this books are being return now. What i want out of this issue is be refunded all the money i paid for the books and can't accept the offer of buying books from me at 40% less of the total amount i have paid.