incorrect declaration. I must pay penalties

I ordered my ring last year beginning December and it only arrived with TNT in Jan 09.2016. Customs stopped it to inspect and the export invoice was only 10USD. The put a hold on it to verify value I sent invoice for R2371 and POP and now I must pay R2900 for penalties and clearing. I call Jeulia and they tell me they put the value down so I wouldnt have to pay so much duty. Then that I must pay R600 more and they will send me a new one in 1 month. I had to chase TNT to find out what is taking so long as I wanted to propose on the 13th but couldn't cause of no ring. JEULIA don't want to take any responsibility and I advise clients not to purchase from them at all