Unable to change Mobile abonnement

I am well over my mobile contract time period and can’t change my mobile abonnement online because My KPN website doesn’t show any option under - “Kies een ander abonnement”. Is cancelling the mobile subscription the only option now? If that’s the case I will rather switch to a different company than KPN because it is terrible that they make it difficult for the customer to be able to choose the product of their own choice. Can anyone help to solve this problem?