Regulations about the compensation company's fee

Hi, I'd like to ask if the claims company who I asked for the help has right to take the fee.

I contacted the only when the insurance company of the other driver proposed to me ridiculous amount of money as the award. For the total damage to my car and the injuries thay wanted to give me only £17 500. As I was not satisfied with this compensation I signed the contract with some company whoose solicitors were suppossed to fight for the higher award.

I have to admit that I was not happy with their sevice:I was not informed, whenever I contacted them my contact person was unavailable, when I reached that lady she was talking to me about the cases of other clients and I had to explain her every time who I am... Finally, the solicitor informed me that I will be given £18 700. I was shocked when they ssaid that they will take 20% fee and they will not deal with my case any more. Ater the fee I am supposed to get below  £15 000!! Is it possible to mislead clients like this? I feel cheated and disapointed..