Well, it sounds like, if you have the correct model selected on the TX, that the TX itself is bad and either needs to head for the shop or trash (or retirement on the shelf). Since it's two years old, you'll have to consider that you may be looking at batteries in another year or two (I get suspect of batteries on a TX after about 3 years - probably just from the way they used to last 25 - 30 years ago though), so you may want to factor that into making your decision on what to do.

If it was me, I think I'd send it in - Radio South will give you an estimate before repairing it letting you decide if you want to go that route. If you don't then you are only out the shipping - cheap gamble I think.

Hogflyer

edit: If you do send it in, you may want to send in the receiver that came with it just to have that checked and tuned while they are at it. It may be worth a call to them and see what they would need for you to send with it.