Transmission problem... Signal loss in RG6 Cable

Dear Sir,

We have installed CCTV cameras at our brick yard which is 1200 meters in length. The cameras are installed at different locations & all the cameras come together at a switcher which is 1200 meters far from my office where i wish to view the cameras on my TV. In that case we have taken an underground RG6 cable (pure copper ) in an PVC pipe from my office to the point of switcher (distance is 1200 mtrs) & in entire cable there is only a single joint at 1000 meters only, We manged to do all the work effectively unfortunately the video quality which come to my office across 1200 meter is black & white instead of the color videos as my cameras are color + night vision equipped. We tried to find out the fault as we discovered that 1000 meter where there is joint til there the video comes color( we took the tv at joint & checked it there), however after a joint there is 200 mtr more cable & at 1200 mtr the signal again gets black & white. We also did vice a verse in case 1000 Mtr & 200 mtr the video till the joint is absolutely fine. The the connectivity of the cable is all perfect in the entire stretch the entire cable is of one make.

Later we asked a local Tv dish wala to help us in this matter.. The cable person who visited us tried experimenting through his module & Amplifier however he was shocked to see the loss of 7 dp per 100 meters., which according to him is more than the general average of 4 dp per 100 meters. When the guy gave 102 DP from his module to the RG6 cable at the 1200 mtrs the DP mtr showed zero Dp, but at 1000 Mtr joint it showed 32 DP. Later when he even connected his amplifier to the module simultaneously to boost the signal from he starting point in this matter he manged to start the signal at 132 DP & at 1000 meter joint we found signal of 63 dp & 33 Dp at 1200 mtr respectively. However this signal was just little better but not something which is actual quality.

Now my CCTV service provider is assuring that the high capacity video balloon + the amplifier will solve the entire problem, please guide me whether my CCTV service provider is making sense or is he still experimenting. Our service provider is from mumbai I want to know whether a amplifier or balloon will really improve the video signal significantly to receive color video instead of the current video quality which is black & white. Now that I have invested in RG6 cable please guide me with a remedy to solve the above problem.

Awaiting your positive & prompt response!