My line is blocked but I do not owe them any money

I had a bill of R2279. I paid R2000 through a bank deposit in two different amounts of R1000 and sent them the proof. A debit order of R349.93 went through on the 1st of December but they deny that this amount is in their account. I have sent them proof of this on the 09 December but they proceeded to block all my lines. I had been calling them for the past 5 days in an attempt to resolve the issue but all staff have a bad attitude and told me I can find another supplier of I want to.