How do you all feel about parents telling you that their child needs to be woken up at a certain time?

I have these parents who obviously think I work for them. Always showing up late. Which has started to stop because I charge them everytime and told them if this continues to be a problem then they will be terminated. Anyway the mom is always texting me at random times sometimes late at night sometimes on the weekend. Which I don't mind but the others parents have the decency to not do it. They completely baby there daughter so she acts like a total brat when they are around. I'm talking won't eat or sleep for them and has a meltdown as soon as they walk in my door. She eats everyhing I give her at my house and sleeps fine.

Well the mom seems to be blaming me for her daugters sleep issues. I put the kids down to nap at 1 sometimes 12:30 if they are really tired but not usually. There daughter is a great sleeper and sleeps anywhere from 2:30 on a bad day to 4:00. I don't believe in waking a child up before they are ready because they are always grumpy and that personal time I get to spend with my son in the evening I want him happy. Last week the mom asked me to always make.sure her daughter is up my 3:30 which she usually is so it wasn't a big deal. However on Tuesday I woke her at 3:30 and she was incredibly grumpy and tired. Now mom texts me this morning saying this

We are having major sleep issues right now, if you arent already, can you make sure she's up by 3 that would be awesome!

I really don't think this is going to help there situation as I think it's a behavior issue not a sleep issue and I don't want to have to suffer with a grumpy miserable child just cause mom thinks she will sleep better if she has a smaller nap.

I would love all your opinion on this, should she be woken up early and I need to suck it up or is the mom putting her issues at night on me?