Change two step verification code setting to email only

How do I change the two step verification code to be sent to my EMAIL ONLY??? I've tried the Don't Ask Me Again On This Device box -- that does NOT work at all; it still keeps asking for a code. I've tried clicking on Use Email --- that worked, but the code was sent to my email AND my phone. I DO NOT have unlimited texting on my mobile phone and have already been charged over $60 extra for texting overage because of the code texting. I refuse to change my phone plan to unlimited texting because I'm on a fixed budget and have a very affordable plan right now. I've turned off the two step verification; would like to turn it on again for security, but only if I can get the code sent to my email ONLY!!! How do I do this? Thanks for any advice.