nashua mobile to vodacom

i had contract with nashua mobile contract fully paid up till 31 december 2014.i got proof of payment.i paid vodacom for the month off january and my next payment is only due on end of february.igot this contract for the past 13 months.vodacom is refusing to hear me out although i am fully paid up.they block my line.i queried five times for same problem with no luck.please can some one help me. thank you...devan