4k wireless box Xi6 and customer owned modem.

I currently have the Xfinity XG1V4-A DVR box, a Net Gear CM2000 modem and (1) Xi6A wireless 4K box.  Went to local Xfinity store to pick up (2) more Xi6 boxes.  They would not give them to me because I did not have Xfinity X1 Modem.  I informed them I already have a Xi6 box which I got 6 weeks earlier and it works perfectly with my modem.  They said to call the 800 #.  I called and they said that 2 boxes would be shipped with the self install kit.  After 10 days and no boxes I called again and was told they would not ship the boxes and let me self install.  I could only get it done if I paid $100.00 to have a Xfinity Tech. come out and do the install.   What changed in 6 weeks?  Is there a way to have the shipped and let me do the install.