Overcharged and rude consultants.

I recently settled my home choice account and I realised that I was overcharged. I received my order in January 2018 and only started paying in February 2018. My settlement letter only reflects payments made from September 2018 to March 2019. I've got receipts that prove that I was paying the account from February 2018. What makes me mad is that when I re-calculate all the payments I've made with interests and monthly service fees deducted it shows that I was overcharged. When I asked one of their consultants why I was overcharged he clearly asked what else do I want because I've settled my account, I'm never ever going to buy anything from home choice dey are just a bunch of ****s.