Disgusting service and theft

I have been a client of Vodacom for over 15 years. I have 3 phone contracts with them and a large fiber contract. I am so disgusted with the way I am being treated. Vodacom has been charging me for a devise that I don't have for 2 years and airtime for this devise for almost 3 years I have been battling to resolve this since May 2018. I keep getting reassured and messed around so that they don't have to refund the money they have ****** from me. I have spent so much time talking to one representative or another and still I have had no one who has resolved this matter. Now they've messed up our existing phone numbers because nobody can understand a simple instruction. They want me to get an upgrade!!! How on earth can I have any confidence in this company after this disgusting treatment and theft? The staff in the Vodacom shop told me I can give up because Vodacom won't ever help me.