IS THERE A WAY TO SET A USER ON PERMANENT - Reply with Message | Incoming call

Currently our system is set through IVR to dispatch automated text messages when certain departments are closed. We are doing this by integrating a user extension assigned to a line on phone wagon.

For example... customer wants to junk their car for a fixed price of $200 and can submit their information with a link thats dispatched through text. Customer presses 1 and that user is and extension that rings a line on Phonewagon. The phone wagon extension does not answer but is instructed to dispatch a predefined text to that customer allowing them to submit their information and dispatching the job.

Recent changes now charge us $59.95 for each text extension we have. This is ridiculous especially that Ringcentral has text messaging capabilities. So my question is, can you administratively set a user setting to reply with a message only when that extension does not answer? My phone bill has pratically doubled from $600 to $1100 overnight and we may be moving to vonage. I like ringcentral and have been with them for 10 years. But this is a bit crazy.