Possible to turn of wireless function, but keep Ethernet function?

How would a wireless extender function if the wireless were turned off? The difficulty I have is in understanding how you wish to have it function if the wireless is turned off. Now - you haven't told us which wireless extender you are using - and quite frankly I'm also having a difficulty in understanding how/why the extender would/could be interfering with the network you're extending, and why the ISP thinks your signal is interfering with theirs. Maybe I'm missing something, maybe the ISP is doing something unusual, but, in general, wireless extenders don't cause problems for the network they are extending (it wouldn't be much point in having them if they did), so I'm curious as to what the problem the other users are experiencing is and why the ISP feels that your extender is the cause. Under normal circumstances, a wireless extender is configured to repeat the existing signal, so it will be on the same channel as the network it is extending, and can theoretically interfere, however, the WiFi standards that dictate how the devices interoperate make provision for this, and whilst contention for bandwidth, it is no worse than if there was another Wifi network on the same frequency.