stop payment on check - california

i am in los angeles county, california, so of course would need info that is state or county/state specific: i wrote a check to my veterinarian for services rendered (surgery/antibiotics and pain meds) to my pet, took my pet home, and then found that the services rendered were not "up to snuff." i complained, suggested that either they provide additional care for my pet without further charge to bring the service up to the par i'd already paid for, or else give me a refund of part of the cost. they refused either, saying i'd need to pay extra for extra services and that the charges for the original service stood. they didn't agree they'd provided less than the originally agreed on and paid for services. so here's the bottom line: i stopped payment on the check! and told them to take me to small claims court and we'd let a judge determine what amount i should pay. they said, and continue to say, that they'll simply file criminal charges on me, that it's the same as writing a check for insufficient funds. i say no, it's a civil matter, a dispute on payment vs. services. so i'd like to know, from a legal professional, which of us is correct. i can't believe a stop payment is the same as an nsf. in fact it's NOT the same, so what i guess i can't believe is that it would be treated the same. otherwise what's the point of the existence of stop payments on consumer accounts??? thank you for any help you can give me. and please indicate in your reply if you are an attorney, paralegal, etc, or just another consumer trying to help out with advice. again, thank you so much.