not invited to renew ...

So I had a little bumper accident earlier this year with my car. First accident in 26 years.
My front bumper had to be replaced and the taxi needed some bump taken out his door. Nothing major.

I get the expiry notice from my insurance company for the insurance due in December and there is this little note : "Not Invited to renew"
What?
Not, you loose your no claims bonus. Not we're going to charge you and exorbitant amount for insurance. Just Not invited to renew? 3rd party insurance is compulsory here, so are they actually allowed to not insure you?
I phoned the company and got someone on the line who had no idea about anything and just said, no you're not invited to renew and would shed no more light on the matter!
What should I do?