Incorrect eBucks rewards for March fuel purchase and rude agent

I have received incorrect fuel spend rewards for the month of March 2021. The bank did not do anything about it until when I called them and the agent by the name of Lucky Enoch tells me they knew we were going to call. I did not get rewards for the 20th usage as well as the 31st usage. The agents tells me they had a system problem on the 20th and I can't get rewards for the 31st because it was last day of the month and he refers me to their Tc & Cs which means the Tc&Cs work only when it suits them. Lucky is rude and won't even let me talk