Waiting for refund.

I app**** for a contract at Vidacom in October 2015 and asked for my MTN number to be ported to Vodacom. Although every thing were approved I was not connected after 3 weeks. I then cancelled the contract and the first payment was refunded. Since then 3 contract payments were taken off my bank account before I noticed it. In April I contacted Vodacom and although no further debitorder payments were taken off my bank account, i have not received the 3 months' refund and have received about 50 calls and sms's asking me to pay my outstandibg account. I have not received one invoice during this period. Needless to say I am back with MTN.