Modifying order within 72 hour window

Has anyone successfully done this? We submitted the order over the weekend and I emailed them today to change the length (from 112 to 120 on a sectional. I tried to call but doesn’t appear the number is working, and the live chat was not active. They finally emailed me back that I’d have to cancel my order and reorder a new one. I told them no since I had other items in my order including a warehouse sale item, 1 of 1 available. I asked if they can cancel just this sectional, so i could order the updated sectional, but would want the 2nd shipping fee voided so im not double paying. They went radio silent….

Any tips? They have a specific section in their FAQs about allowing modifications for free within 72 hours so unsure why this is an issue, as there were several length choices within the options for this couch. Any idea a better way to get ahold of someone?