Online order gone wrong

This is was my first and last online purchase from Leroy Merlin. I bought a corner patio set online, the delivery was late but that's ok bcos it finally came even if it was 5 days overdue. Once opened, I realised that what I ordered was not what was delivered. I called Leroy Merlin and I was promised a replacement within 24-48hrs. It's been 10 days of being sent from pillar to post. Totally unacceptable! Even the patio manufacturer, Calasca is not answering any calls!!!!