Business Line locked

My contract with cellc on *** ended last year in October(2015). I admit I did not cancel or upgrade the contract and they put it on month to month contract. Now when i request that i want to cancel and port my number back to Vodacom, they tell me they cannot access my account as it has been handed over to NDS. I have been making payments and i contacted NDS and they told me i dont owe anything anymore and should go back to CellC. I went back and they still cannot assist me and refuse to contact NDS to sort out the problem. I want to settle the account if need be and port my number back to Vodacom as i use it for business. Currently clients are unable to get hold of me and its costing me. Even today i contacted them but in vain. I need my number working please and if there is payment due i am willing to pay. Please help this has been going on since November 2015