Bad Service + unnecessary chargers

I took a loan of 2000 with African bank in November 2014 they debited first installment end of November and in December they debit my account twice and i went and reversed one installment . in January 2015 they didn't debit the last installment and i only realized that now because i checked that on their online system and they have now added arrears to my installment because of something they failed to do. i spoke to an *********** call center agent who doesn't know her job she wasn't able to answer my question and again she hang up while i was talking to her