Iphone 6 car kit. Help please.

Hi All

Just wondering if there are any "tech heads" that can help me with the following.
A few months back I had carcom in Darwin remove my old car kit that I used to use with the old Nokia 6120 and install a new one for the Iphone 6. They also installed a new cable and antenna.
I use the car kit for one reason, to get extended coverage, that it charges the phone is a bonus but this can be done with a cigarette lighter adapter for $2. I don't use a mic set up (troopy, you would never hear it anyway). But just sit it in the cradle and use the phone mic.
My problem. I get no further range with this kit. When down on the Roper a couple of months ago I had to get out of the car to get a signal.
With my previous phone, if I got out of the car and got one bar signal strength I'd probably get 3 bars with it sitting in the cradle.
This was repeated just the other day with reception out of the car (just) but not in the car. I went back to carcom about a month ago and was told as it uses a "capacitive" coupling it doesn't work as well as the old type. Well, OK, but this just doesn't work.
One of the guys came out and we tested it by going into the phone settings and ringing a certain number, you then get a signal strength reading from the nearest tower. Sometimes it was a "little" better in the cradle sometimes not.
He suggested I try this when down at Litchfield, I never got around to it. I figured what's the point of stuffing around to prove that if I dial the tower 20 times and 13 out of those 20 calls the signal is a "FRACTION" stronger big deal.
From my point of view I have wasted my coin, we only use it when we go semi bush. I should have just left the old kit in there (still have the old phone) and pulled the sim card out and put it in the old phone if I really needed to use it. Yeah, I would need some sort of card adapter to fit the micro SD card.
Your thoughts folks?

Thanks

Lyndon