Again, Apple has nothing to do with any charges for sending text messages. Apple has no such charges. Whoever at your carrier told you to contact Apple about this issue is either ignorant of their own policies or trying to foist the blame because they don't want to deal with the problem or explain an unpopular policy of theirs. The same applies to your Messages not being able to turn on texting through your carrier. Text messaging via SMS/MMS, i.e. sending messages to a non-Apple device, is completely a carrier-based service. Call your carrier back and don't let them foist you off; it's completely their issue to solve.
Regards.