Amount paid not deducted from total amount owed

On Monday I paid R500 and today I receive an sms from Telkom that they have not received any payment from me and that I owe them R1226 and they will switch off my line in 48 hours. Please try me with that *******, I am ready for you. I called Telkom mobile 081180 number to check amount owed and my payment was not deducted again I owe them R1226. Telkom mobile is a useless ****** company, I regret the day I walked into that store to get a contract but I want to make other people who might think of taking out cell phone with this company very alert. They must try Vodacom and cell c for peace of mind. My contract with Telkom ends in October now I cant wait for October I want to know the settlement amount for this useless company.