if you 'attract' a loading as well as losing your NCB, you should write a formal letter of complaint to the manager of the company, seeking a proper written explaination for this. if not happy, write again and if still not happy, write to ombudsman.
Losing your NCB is punishment enough. you should NOT have to pay any penalty loading unless there were adverse features relating to the accident, such as conviction, failure to co-operate with insurer, frequency of claims etc