We had a situation like this with last teacher (except the problem is math--she was giving him 5+2 math when he is already capable of long division). At the beginning of the year, with the principal present, she agreed to give him harder math, including harder math homework. It just never happened. The more I asked (nicely) about it, the more stubborn she became until she wouldn't talk about it at all. She did not give any differentiated work in class or even enrich the first grade math.
I ended up pulling DS out of the school, which was an option for us due to open enrollment. I wasn't going to deal with a teacher who wouldn't even communicate with me.
New teacher--totally different, said yesterday "He WILL NOT be bored in math from now on." LOL. She saw his achievement scores (since she has a master's in special ed she actually understands the Woodcock Johnson) and gave him harder math on day 1.
So just so you know what can happen. If she won't comply, then what? Are you Ok with still sending him there? It's sad that parents have to even consider what they will do if teacher ignores reasonable requests or becomes passive-aggressive.