The worst service I’ve ever experienced!!! I’m so shocked !!

I have never in my entire existence experienced such awful service OMG I’m in shoc****! So last year I bought a set of pots and took a payment plan of 6 months.. so 6 months later I get a call stating I’ve been handed over to their collectors for non payment, naturally I call to find out how that’s possible... their response was even more shocking , I was told they haven’t been debiting my account and they don’t know why.. i was put on hold for a while and then was told they would call me after an hour as their still investigating.. no one called me!! After about a week i receive a call from their very rude collectors agents asking when they should be expecting payment, at this stage I’m so gatfull I agree to an arrangement of half of the balance for the coming Friday.. which was debited .. the Monday after I get a call stating the balance has now increased and they need 900 immediately or they’ll blacklist me ... mind you they’ve just debited half of what was said to be the balance last Friday and said they would debit the rest on the 25th.. I’m so annoyed I’m fuming!!! Some girl then calls me again today and was so rude talking at the top of her lungs when I told her not to be rude she then not hangs up.. like I’m so done with this company.. I want nothing to do with them.. no one wants to be accountable and their agents are extremely rude!!! I’m still in shock as I type this