Sorry I removed your last post out of privacy concerns. Your first step should be to contact your reseller as they might be able to get the unit operating correctly for you.
Failing that, you can open a case with us (and there attach your invoice 😉 for a replacement MM2211.
WRT getting a different device..again you should discuss with your reseller. From your description, I don't think the MM2211 would provide the coverage you're looking for (and in fact will likely be a challenge for any single device). Our ZF7982 is the most powerful single device we have, and is what I use myself. However multiple APs and/or a mesh network (which requires a controller) may be required in your case...your house is bigger than my entire lot and we play football in spaces the size of your garden 🙂