Unauthorised debit order

Comprehensiveguardian is debuting my account by force even if I don't have contract with them,so please assist me to stop this stupid people.Absa: CHEQ2681, Sch t, 27/07/18 SETTLEMENT/C - NAEDO TRACKED DO, SLZ /NEW5425, R-89.00, Available R7,977.85. Help ********** 600; SETSEMA026

'SLZ ' lodged a R 89 debit order for date: '180725' on your acc. For queries call ' ********** 951' ref: 'new5425' or for more information go to 'http://comprehensiveguardian.co.za/'