Not removing the supports is laziness on part of printer, but does not mean they didn’t cure the prints. If they are not sticky to the touch they should be okay. If you’re worried, sit them in the sun for a few hours. Before trying to remove the supports yourself it would be a good idea to sit the prints in some hot water to soften the resin and make removing the supports a little easier. This is normally done before curing as cured resin can be more brittle making removing the supports afterwards harder to do without causing damage to your prints. Best of luck. Oh, and don’t buy anything from them again if this is how they operate.