Debit order with no authority

I received a call from the call centre for this product - pay monthly for shuttle service when you require it.<br> I refused the offer but just received a message to say that their will be a debit to my account<br> <br> I did not authorise this debit order but cannot contact them as the number provided keeps giving options to select, but when selected, it loops back into the original message which gives options. <br> <br> VERY FRUSTRATING