Incorrect info given to client

i have a rental vehicle with Avis that was though my insurance untill 20/05/2015<br> on the 19/05/2015 i phoned in to extent the contract on my own account for two days which the lady said she had done but however today i get a sms to say i have to return the. It was such a struggle to try and rectify this and to top it all off they give me the wrong contact number? How is this possible I kept my side clean and phoned before now i look like the culprit?<br>