Unhappy C.

Bought a dishdrawer and staff at the shop was very helpful. However, on the day of the installation, the team said they could not proceed because the water valve wasn't the correct type and to call a plumber. Of course, I am not a plumber so there is no way to say if they were right, but ever assuming they were, my old appliance was left in place (while the disposal should be included in the delivery fee which I paid). Calling the customer service was useless as according to them: A new installation would cost me again just to make the team drive back. The removal of the old appliance would cost me again (can't understand why really, they left it here with no reason, even if we asked to remove it, but we just assumed after the plumber to call them back) and top of all: no return as the package is already open?!?!?! They opened it and failed to install (this part could be my fault, but still) and now I can't even return it. So now I am stuck with my kitchen in a mess and have to call someone else to fix that.
Don't know what's worst about this, but I am pretty sure it shouldn't be allowed to refuse the return because package was opened by their staff...