Bridging of contract

I am unhappy with the way Vodacom handled my account.

2016 i took a contract with Vodacom the agreement was i pay R350 monthly and get R350 airti monthly, it went well for some months until the airtime use to disappear within a day, i called them several times telling them about the problem but they never resolve it, i even changed the phones from SamsungJ5 to Huawei but still the same that is when i stopped paying the account they called me, and i told them to fix the problem and i will pay,

then they handed my account over to BURNARD RAAFF of which they are now threatening me about Garnish order, court case and have sent sms's that i should make payments today and they are telling me about Bridging of contract fees that i was never made aware of during the period of taking the contract over the phone. please help