Debit order

i did a Trade-in on my car and i requested for Tracker to cancel/Terminate the contract for the old car and install New one in a New car. so they Debited the following amounts: DB24JGGP Settlement amount @ R800<br> FY309186 Pro-rata Jun 2015 subs @ R20.98 as installation was concluded on 25 June 2015.<br> FY309186 July 2015 subs @ R126<br> FY309186 Aug 2015 subs @ R126<br> <br> which i understand them even though i do not Understand that R20.98 but its fine. my problem is on the 1 July 2015 they Debited R139 which this is for the Old car which i cancelled and i do not know why do they did this. they are not giving me answers of why did they Debit that R139 in July