Unpaid Cashback

Was expecting cash back as per the communication from iWyze that said should I not claim till 31 of December 2020 I'm eligible for cashback on my anniversary of which was on the 1st of April and I called to enquire and I was told that I have one month that they didn't receive the premium so I won't be getting cashback I had this insurance from 2015 and I haven't claimed. I'm not happy at all