How does a R4500 debt turn to R12000?

I had a loan with Capitec in 2009 which I struggled to completely pay, the outstanding balance in 2010/11 was initially around 4500. This account was then handed over to A van der walt attorneys and I had had no idea all this time. Upon calling them I was told that the balance is now close to R12000, like, seriously! how did it get to that amount? I mean this is really strange. What's also strange is the fact that the account was handed over to them in 2011 yet since then they have made no effort to contact me, they have not called or sent me any letters. I asked the lady I spoke to at the call centre to give me the address they have on their side, and to my surprise its my residential and postal address, yet no letters where sent there. A while back I was notified that they confirmed my employment with my employer, strange that they could track down where I work but made no effort to contact me directly, it seems like their goal is to just make their money off sitting on accounts to accumulate these ridiculous balances and then eventually garnish people without actually trying to make arrangements or contact. This firm seriously needs to be reported to the Ombudsman