Billed for something I never even received

<p>Got an sms from RNB solutions this morning,phoned them and now I have R900 outstanding on my account for jacklin Enterprises apparently..I had R639.20 outstanding where I paid half due to only receiving the one part of the parcels...I never received the second part (have the e-mails requesting it but never received it)I sent the proof of payment to RNB last year already with all the attachments...a year later the contact me again saying I owe more than R900???to me this is theft!!why didn't they contact me immediately?I did pay for the parcels i received, but why do I have to pay for something I never received??</p>