MISSING PAYMENTS

My name is T.D Sibisi.On the 19 of August 2015 I made a payment of R5000 at Edgars using my store card, Acc.no.*** and on the 25th of November I made another payment of R3000. The problem started when they called me saying they didn't receive payment.I have proof that payment did go through and and some shop employees say they can see it but for some reason they can't access it.I took this matter to their management and as from the 9th of December they are telling me that they are still investigating.There is no communication from their side and each and every time I call I find someone new who asks me to start the process of sending proof of payment again.The lady from the head office is always on leave.What worries me is that they keep asking me for payment and I'm worried that this might ruin my credit record.Please help.