Yep. Do this!
I had a commercial acct act very similar to what the OP is experiencing. All was good in February, started cutting 1st week of April. They call the 2nd week in April to let me know they had contracted someone else for this year(news to me). So I said ok, took them off the schedule and went on about my day. 2 days later she call me again, well their “new guy” fell through and wanted to know if I could pick them back up. I said absolutely but the rate has increased. She asks how much, I reply - $40 per service. Never heard from them again(so far anyway). I have 0 patience for shady bs games.
I agree, the thing that really grinds my gears is that in the clients eyes, an email saying they accept the quote on October 26th, is the same thing as the signed contract which sent on October 30th(which was never signed!) The other thing that blows me away is what people will say via text or email, but would never say in person.