Bad service

Bought on the app bash on acc, a 12 month instalment plan and the amount due was somehow turned into a one month plan which was a huge amount I could not pay in just a month, sent an email and I never got a response, called the contact center and I was told different stories, fist consultant told me he was going to get the team leader to sort it out and the amount due to be adjusted, admitted the bash app was still under construction and had discrepancies and another one told me that I somehow chose an option to a one month instalment when I checked out Wich has never happened on the old app and how is it possible that my account is and has always been a 12 month plan and when purchasing I again have to chose again. When I asked the consultant they couldn't give me a straight answer and when I asked for the issue to be sorted out because the fact that their systems had discrepancies was not my fault and this will reflect negetively on my credit report, the consultant told me it was not theirs either and there was nothing they can do.