No contact since I started working but I receive a JUDGEMENT on my name

I was offered a contract in 2011 for a phone by telkom mobile but unfortunately after that, I lost my job. I could not afford to pay for the contract and did not have resources to actually call and organise something with them.

When I started working in 2016, I contacted all my old debts such as Markham, and Truworths including telkom but I could not get hold of telkom for months on end, they kept telling me the account is sold to a collector but the collector denied having the account on their books.

Yesterday i received a judgment alert on my Transunion Profile which affected my score and profile negatively from Telkom. They never contacted me, I have current debts running now and I'm paying all of them well, I have never skipped a payment since I started working. Had they got hold of me, there was no way I would'nt have agreed to pay for this. Again, this is an old debt and hasn't the alleged debt prescribed"? Now there is a judgement against my name after working so hard picking my profile from the poor category now its back there again for a debt I was never contacted or followed up about, this is not fair. Out of nowhere, you just raise a judgement against me, without even contacting me, this is uncalled for, its bull****!

I made efforts to trace it but I could not find it and the help was not adequate enough from Telkom. Clarity is required in this regard and this is a five year old debt.