Vodacom ruined my life

Vodacom ruined my life.i took a sim data contract from vodacom and after moving to United Kingdom i has to cancel it.i called them and they advised me to pay a penalty fee to cancel it.i paid the penalty fee as asked and email all the relevant documents to them.Their agents did not do their job so now it states that im on arrears yet i requested them to cancel the contract since im leaving the country.I cannot buy anything in south africa because of vodacom this hurts deeply.