********** activity from lewis itself

my mom took furniture at Lewis Eldorado park, all together she was suppose to pay back R14 168.88 for the 24 months through monthly repayments of R590.37 per month as stipulated in the contract given to her on the 1/5/2014. her first payment was on the 28/6/2014 for R595.00 there are months that she paid up to R1075.00 and R1100. Lewis threatened her with an SMS stating she is in arrears. up to date as per the slips she paid R11 940.00 which means there should be a balance of R2228.88, which the first payment for this year should go off, the final amount should be at the end of June 2016 then the 24 months is done. she received an sms stating she is in arrears and she is being threatened with Lawyers saying she still has to pay R11 447.78 where does that come from? when we went to the store they advise their system is offline we went there from the 21.09.2015 and we still did not get an answer, we call head office they do not want to hear our side they say she must pay or she will be listed. she is not working at this moment we as the kids assist with payments . please assist