NO CLAIM REWARD

I've got an IWZYE insurance policy in which I was supposed to get paid 3 years no claim reward bonus.I got a letter confirming the reward and the sms which stated the date in which I was supposed to get the reward on the 31 march 2015.on the 2 of april I called them to enquire about the reward which I never received and that's when I was told I missed 1 month payment which old mutual never received.I am ****ed of by old mutual because the next month the deducted double the instalment I am also angry why would they send me a letter and an sms confirming the reward.they take money from hard working people but they cannot give back the money they promised to give when you don't claim I am going to cancel the contract with them old mutual is unreliable and not customer friendly