Poor Service

I've complained about this company 3 weeks back, my account is still in arrears with them, i returned stock and sent proof of waybill, reconciliation sheet and Picking Slip but still it has not been credited back into my account. I have sent several emails to their credit crontrol and queries department, with no response. When i call their head office both my ID number and my account number are not recognized.

I just want them to credit my account then close it and send me proof in writing.