I canceled my membership a over a year ago and out...

I canceled my membership a over a year ago and out of now where I start getting emails that payment is due. It's been two months since these emails have started and they seem not to care or do anything about it when I remind them again and again that I canceled a year and three months ago. If this has happened to anyone else I would like to know. I've been keeping records and if this does anything to my credit there will be hell to pay.