Hi Dancergirl! I have taught a bit at state non-selectives and our daughter is at Henrietta Barnett, a grammar school. ... I was sorry to hear about your school's English lessons.
I fully concur with previous posts; I especially echo the comments of Roseformeplease.
One of the problems with the indy schools is that they can do what they want and often get away with it. Only publicity, or the threat of publicity, corrects some of their practices.
At HBS they do vastly more than you have described. Good reading, sound comprehension and good writing are a feature in all subjects , includind Design Tech and History. This brings out English Language learning points, including good grammar in the context of effective, fluent writing in a variety of styles.
The English Lit texts read and studied are many and numerous, with lots of inter-form Drama competition, school productions and frequent theatre visits. Literary/Historical themes can cover lessons in English, Drama and History and form the core of Themed Weeks once a term. Some of the quality comes from the school, much from the girls themselves.... It also helps, I guess, if Mum or Dad are big readers and enthuse about this stuff (in between Eastenders and Friends reruns!) Not all parents are or can spare the time, especially across all their children... I should add that the HBS Head of English is mad keen on reading and theatre for herself and this rubs off.
So, what do you do? ... Ask around. What do other parents feel? Would at least one otehr write to the Head? Would at least one other write to the Head of English? .... Maternity means teacher changes can be frustratingly frequent at any school, but whatever the reason your school's position is not great. I would be tempted to to send a detailed letter of concern, signed by both Mum and Dad, and monitor developments. This letter should go to the Head, cc the Head of English. And then, if they try to get you in and pacify you, I would politely decline. They should write a detailed response, not fob you off; they should acknowledge responsibility and tell you their plan for change, in writing. You are the parents, you pay fees, you are the client. .... Hope it works out.