MRP Mobile is refusing to pay back the amount they debited from a bank account for a payed off tabled.

In September 2015 my mother got a call from Mr price advertising a tabled.She took the contract option but later changed her mind and paid R1837. 55 cash on 2015-09-25 (The same month). On 25-04-2016 MRP MOBILE debited R1837.55 from her bank Acc. Same day she attempted to revers the payment but it never reflected in her account /bank statement . Few days later she got a call that she owes MRPMOBILE tablet. Days later shebwas handed over to their attorneys with daily threatening calls and smses. She faxed the proof of payment and copy of her bank statement that shows the debited but she was handed over to MBDLC Attorneys. She was harassed and intimidated through calls and smses continued through calls and smses by different debt collectors for 5 years. The issue was then resolved after involving her lawyers but Mr Mobile is refusing to pay back the money they debited from her account.