Over charged

I'm very disappointed with multi choice I've been over charged by this company for the past 3 months of which I was calling all the time, now last month I payed money into their account which I saw on their app and they also ran a debit order a day after I payed then I reversed the amount now my services have been suspended when I check how much money do I need to pay they have charged me twice of which I payed my monthly subscription. I want them to explain how do they get to the money they are talking about.very frustrated with this company honestly.