Tux, if you want to be heard please keep everything to a single thread else it's impossible to follow.
Before demanding your money back I think we should first find out if the walls are broken or not. NIC is hardly important whether you spent 1 billion or 100 billion. It's all fake money.
First things firsts, walls are plants. Walls probably NOT intended to die like plants. Walls MAY be designed to slowly lose health over time while also growing (And increasing their health). This could mean that final stage walls require a weekly maintenance to keep them above 50% health however I find this very UNLIKELY.
Secondly, the devs have done this before and can do it again. They can remove every wall unit from the game, refund them, roll back the terrain layers (Possibly very hard) and be back to where we started. They can then patch the wall death bug and this issue goes away and walls are back to being spammy, annoying and filling the sandbox with poopy sand rather than pure sand.
Finally, if this IS an intended feature it was not documented correctly and refund should be given to any deployed walls and the feature continued and maintained. It's really not hard. Please try to keep a level head. It's pixels and the devs are hugely reasonable and intelligent people. Well.. Mostly.. anyway..