They are saying I haven't done the volume required as I had received s bonus
Which they did not mention at the time
May be you misunderstood the bonus, there are terms and condition with every broker that you have to be trade certain volume to withdraw bonus with bonus amount.
http://www.insideoption.com/terms-of-use
go here and check
6. Bonus Policy
6.1 The Company may offer a number of attractive reward features, including welcome bonuses, contests and awards to new or existing customers. Bonuses and trading credits rewarded to clients are part of the Company's promotions programs. These bonuses are limited time offers and the terms and conditions associated with any bonus rewards are subject to change from time to time.
6.2 Bonuses and profits that are based, even partially, on use of bonus credit, shall be forfeited in case the Company suspects any act of fraud or breach of the Company's Terms and Conditions by Client.
6.3 In order to withdraw funds from an account that has been credited with a trading bonus, the trader will be required to execute a minimum trading volume of (bonus amount + Deposit) x25.
6.4 Funds can only be withdrawn when the preceding stipulation has been fully met and fulfilled. All trading bonuses are final, and a trading bonus cannot be removed once it has been credited to an account.
PS: Don`t take me wrong by broker favour. I`m just clearing things over here.