Bad Service

I took a contract with Nashua Mobile, and per our agreement they debited my account both in November and December. But I was informed in October that the account had been transfrered to Vodacom. And I assumed that since they debited my account that meant that the money had been transfered to Vodacom. But I was shocked when vodacom called demanding that i pay them for the above mentioned months. I immediately called Nashua Mobile to inquire. I went through to Feroz who asked me to email him my bank statements proving the above mentioned transactions. I did as asked but to date I haven't any kind of feedback and Vodacomwants their money. I faxed the bank statements on the 22nd of January. All i need is mymoney so i can pay Vodacom. Am disappointed in Nashua Mobile because I believe that they should have done all the necessary arrangements with Vodacom.