Bad service

I am not happy with the service, on the 4th of December I bought a phone for R1600 if not R1700 in East rand Mall, all went well.

On the 7th of December I paid R1500 into the Ackerman's account to my surprise 1st week of January I was getting calls to pay minimum amount of R170, then I realised that the payment was not received,

On the 3rd of January I called and I was given an email *** to forward my proof of payment and told that it will take 7 workings days, to my surprise I will be getting calls after calls been told of amount of R675 which I stated that I didn't pay that amount.

On the 12th of January I was requested to send again proof of payment which I send again.

Again, on the 15th I sent another email, today it is the 31 January, no one has responded to me, but calls are keeping on coming regardless of telling them that I had already paid,

Please resolve this issue.