Hi mate. Am soz I wont be able to help you fully but as far as I know, you need to ask the bankers/CC providers to notify the immigration people and do the clearance. You must get a written confirmation from the bankers/CC providers as your proof that youve paid off the amount. And then double chack with the immigration office (next to the Doha airport).
Ask more people just to inform youself wot exactly is happening with the system. Good luck and good day!