Hello Elinore and welcome to just answer Jeep. The ignition switch and key cylinder can be replaced on your Cherokee. I do not know why your mechanic said that. I recommend you call a locksmith and discuss this with him/her. Here is the procedure from the factory service manual for you so you can see that it is repairable You can print this out and give it to your mechanic or locksmith. You should not have to incur the expense of a complete steering column. Hope this helps, and let me know if you need more assistance with this,
The ignition key must be in the key cylinder for cylinder removal. The key cylinder must be removed first before removing ignition switch.
Elinore, If your mechanic still thinks you will need to replace the entire steering column, then send me your Jeep's VIN number and I will look it up and see which column you will need.
the piece you need is known as the "ignition switch lock cylinder" Call your Jeep,Dodge, or Chrysler dealer. They can tell you the part number and quote you a price. Then if you want to purchase it elsewhere, you can do that using the part number they gave you.
Thank you for the accept!