I have to agree with Gareth, it’s certainly asking MTronics at the very least. I’ve always found their service excellent.
Failing that, don’t chuck it away, either pass it on to someone who can use it or use a spare channel to operate a change over switch to get reverse. That’s a bit Heath Robinson I know, but it works.
Just a last thought, My transmitter can have the throttle lever set to give full deflection with the whole sweep of the lever, i.e no reverse, I did that once by accident. I think the aircraft boys set them that way. It’s worth checking the controller with another channel, if you haven’t already.