Thanks for all of the suggestions. I really needed some outside perspective. I was mad at the builder who has been jerking us around for months, and I was mad at the tenant who sent me the obnoxious email despite my keeping them in the loop regarding the builder and the yard install status. There are 5 consecutive lots from different owners all having the same issue.
I think I have found a yard cleanup contractor who can get the work done.
Yes, I would agree that the amount withheld from the builder was not enough. I said so at the time of the signing (it wasn't until the actual closing that I got to see the amount being withheld. We were not told 1.5%, I just figured out the math later. It doesn't nearly cover the costs involved.), but continued with it as I presumed (poorly based on experience) that the builder would follow through. I had independent contractors scheduled for interior tile upgrades and I didn't want to delay the contractors and the tenant move in date based on the hold back amount. Sadly I now know better for the next go round.