Poor customer service

Rain mobile, l have 2 4G mobile simcards from Rain. I use sim1 on my phone and sim2 is not in use. Yet every time l check my balance it shows deduction on SMS’s and data from sim 2 which l am not using and minutes are deducted on the correct sim which is sim1. Every month the agents tell me they are investigating and never revert feedback. If l run out of minutes on sim1 l cannot insert sim2 on my phone because it has no data but l have not used it. Everything should be deducted on sim1 not half on sim2 and the rest on sim2.