Benny -
Insurance companies can quote whatever they want. Like a shop or restaurant they are under no obligation to accept anyone as a customer. If a shop or bar thinks a customer might cause damage and them money they have every right to ask them to take their custom elsewhere. It is the insurance company who you will expect to fork out a lot of money if you have an accident, so if they think an inexperienced driver is going to cause them to have to pay out a lot of money they prefer not to take the risk.
The problem is that there are far too many young drivers on the roads today in cars that are much faster then a generation ago. When I started driving in 1980, 30mph was damn fast in a Cortina or Viva! You also had to use a fair degree of muscle power and anticipation to change gear, turn the steering wheel and guide the car round a bend! Modern cars are so snappy and fast that when you combine that with an inexperienced driver you get accidents. There's also the fact many drivers maintained and repaired their own cars. If you dented a wing or bumper you just unbolted it and bolted on a new one. Most modern cars have welded panels and it costs a four-figure sum for a repairer even to change a wing! Bumpers are plastic rubbish that cracks at the slightest bump and cost hundreds to replace.
When I was 18 my first car was a Rover P6 and the insurance was £82 a year which everyone whistled at. My boss's Escort was £35 a year! I'm afraid that new drivers like you are being penalised for a combination of three factors - modern car design, modern car speed and handling and the number of youngsters in such cars. All you can do when you find an insurer is drive carefully, stick to the rules and speed limits and build the trust of the insurers. You premiums will eventually come down.