Parking permit

I'm just wondering what the process is for getting the new parking permit. My last one just ended and I've not received a renewal letter or any info on how to get the new one. I thought heard that the old stick-on ones are no more and it's all done by the number plate from now on. Should I still have received a renewal letter or is that changed too? I will call on Monday as it's too late now. I'm just looking for any information on this new process. Thanks in advance