Double debits - Car Track

I joined cartrack last month, paid the prorata fee. This month my first debit order went off as planned on the 26th. Imagine my surprise when today, the 28th, my card declines, only to find out that Cartrack has debited my account a second time? Thankfully I managed to reverse the debit order but if this is going to be a regular occurrence I will be sending Cartrack the bill for my debit reversal charges.