Low credit rating for upgrading

I have been a contract customer since 2012 and have 3 contracts at the moment. I have been struggling with my debit order going off monthly for a while. Even if the funds are available in my bank account for vodacom to go off it returns it as unpaid. I have phoned FNB and they said its set up correctly on there side aswell as vodacom.

I dont always get a sms from my bank to say that vodacom is unpaid, I get a sms sometimes 2 weeks later that my account is in arrears and then I have to go make a cash payment in store and everytime it happens I must pay a debit order return fee, something thats not my problem. They said it should go off end of this month as normal hoping the problem solved. I bring my account up to date monthly even if it was late payment. I could upgrade my one phone line on ********** 642 since march 2018 and that my term is ending 18 June 2018. I wanted to upgrade they wont allow me to because my profile rating to low because of debit order jumps thats not my fault. I get offered the cheapest handsets and cant get the desired phone I want. Its almost like they want to punish me for late payments.

I phoned accounts department, upgrade department and they tried to upgrade my profile rating but failed and my account is up to date , its not as if I'm 6 months in arrears. So if I cant upgrade my device I will cancel my contract and switch to another network. It seems vodacom does not care about losing clients with care free attitude.