Customer Estimate

Location: MO

I have a LLC as a Handyman. I gave an estimate over text and the customer agreed. I then needed to change it based upon equipment availability and ability to get the job done. The customer said what we agreed upon is what needed to be done and seems to be hinting at legalities. No final quote was given, nothing in writing (except over text) and the customer wants something extra added. Can he sue me (and win) for breach of contract if I decide not to do the job? Thanks for any input you can give.