Chris the plumber

Hi All,
My 2007 GC. came with a REC satellite navigation/radio unit fitted, but no reverse camera. I would like a camera, but not at Jeep prices!! I have read the thread on this forum for fitting a Jeep camera, & that the "radio" would need to be programmed to receive the signal. My dealer looked completely blank at this & also said they would charge £60 ($100) to even try.
I have purchased a cheap Chinese camera AND the plug to fit into the REC but so far can't get it to work. If it proves impossible to program the REC "radio" I will have to resort to a rear view mirror with built in LED screen but loathed to do so when I KNOW that there is a screen there for the job. HELP please, Chris.
UPDATE
Since writing the above I have been back to my local Jeep dealer, spoke to the technician, he understood what was needed. The camera needed to be added to the options list for my vehicle, then downloaded to the FCM. He came back 20 mins. later, done & working on the Radio/head unit. AND it only needed 1 wire connection to the head unit, that's the centre wire, cam signal. I'm really pleased, so, spend a few £££ or $$$ on a GOOD Camera from China, wire it up as described elsewhere on this forum, then go to your JEEP dealer & get it "turned on" Done!
PS. they charged £40 to turn it on.