HARASSMENT FROM MR PRICE AND SHEET STREET

I am sick and tired of getting sms's from Mr Price and Sheet Street to pay my account. I have NEVER skipped a payment, but every month I get harassed to pay my account. I DID NOT give them permission to abuse my cell number and I want it to STOP!! The message I get "Maintain the positive credit rating on your Sheet Street account. Pay your instalment of ..... by 31/03/19 to prevent your account going into arrears." Mr Price: "Due to recent purchases at Mr Price, your new installment is ... and due by 3103/19. Pay ... on time prevents your account going into arrears" THIS BULL**** MUST STOP!! THIS HARASSMENT MUST STOP!! I pay for my phone, NOT SHEET STREET OR MR PRICE!! I am NOT a child, I KNOW when to pay my account!!