Money not being paid

Hey y’all need some advice here

I have a customer who is blatantly ignoring my messages now and there is a small portion owing

My contract states 90 days past payment is a void warranty. It’s about halfway there timeline wise. Am I standing on any ground where I can pull the chute and terminate early?

No conversations, no replies back. The agreement on the final price was most definitely an agreed two way conversation and the job is done and they were happy