Higher grade debit date adjustment

After starting a new job with a new salary payment date I requested for my debit date to be moved from the 23rd to the 1st . They advised that they could only move it to the 31st which I agreed to . But now for the last 2 months they are still debiting me on the 23rd so they have cost me R200 and block my device almost immediately and threaten to collect the device . I've sent emails , been on customer support but no one gets back to you . I would recommend going with a more reputable company like teljoy as my wife has her phone through them and never had any problem . I won't use rentoza again