Getting charged on warranty work by a retic company, help?

Hey all

Had my new master valve start leaking water all over the joint so I called the company out to fix it. Because a shut off ball valve just before it had decide to pack it in too (we think they replaced it during the master valve job but unfortunately the quote doesn’t have an itemised list of works they originally did) they first came out to seal off the pipe so we could have water to the house again.

5 days later they finally come to fix the seal on the master valve as it hadn’t failed (their pipe sealing had) and put on a new ball valve (one of the one way ones). He was still working as I left for work and as I left he said he would leave the invoice in my mail box.. kinda confused at first because I thought they were fixing my retic under warranty but though they must have been nickel and diming me on the ball valve that I didn’t have a receipt for.

Turns out it was more than that… to supply and install the valve they have charged me $410 (the part is a $40-$60 part for non commercial supplier) plus they charged me a fee to come out and test, isolate the pipe and also to reinstall the ball valve + master valve (the thing they fucked up)

I’m going to call them to try and figure out what the hell is wrong with them, hopefully there was just a miscommunication and the service dude didn’t know this was a fix of their work but I’m guessing not. My question: Can a company just charge you whatever they like without warning? I never asked for a quote before work starts as initially i was under the assumption this was purely a warranty job. If anyone thinks there is a law for this kinda situation I would appreciate any naming of such as unfortunately sometimes the stick is the only way to get companies like this to not be dicks.