Unreliable support from Cambridge University Press

My kids are homeschooled and I paid upfront for Cambridge AS level text books on 25 February 2021. I received some of the books within 2 weeks and 5 other books were not in stock and I was told that by end March I will receive the books. I have been calling them every week since mid March, & every week I'm told that the books will arrive the following week. Meanwhile my kids who write exams in Oct are falling behind. They do not return calls or respond to emails and you have to keep following up with them for answers. Their service consultants should have informed me to buy the text books elsewhere and refund me the money. Just very disappointing service & support from this company.