Bad experience

I took a Telkom mobile contract with an agreement ogy paying monthly end ,from the in set they took money wrongly from my account I had to pay penalties I went from the stores and complained all they said was sorry,now am about to finish this contract they didn't take money in December and Jan they only took one installment this has left my credit score down as they debit on the wrong date ,when you call their agent all they are saying is nothing but stories Am NOT HAPPY as this was my first Contract in my life now they have ruined my credit score 👎👎👎👎👎👎