Total disregard for customer's needs

I took out an extended service plan for my vehicle in December 2014, as my standard plan only covered me up to 30 000km. This was taken out when the vehicle went for the 20 000km service. (so it was with enough notice). The vehicle recieved the 30 000km service in March 2015, and is now due for the 40 000km service. When I went to book the service at McCarthy Toyota, I was informed that this plan was cancelled due to the fact that no payment was recieved. Due to numerous debit orders related to my vehicle, I was unaware that these payments did perhaps not go through. My complaint is that I was never informed about this, so I could not rectify it in due time. They told me that they have sent an sms, however I DID NOT recieve it. I have been trying to rectify it with them over the last few days, and I am no further than when I started.